Apparatus for RF active compositions used in adhesion, bonding, and coating

ABSTRACT

A susceptor composition that can bond two or more layers or substrates to one another and that can be used to coat or cut a substrate. The susceptor composition is activated in the presence of radio frequency (RF) energy. In one embodiment, the susceptor composition of the present invention comprises a susceptor and a carrier. The carrier and susceptor are blended with one another and form a mixture, preferably a uniform mixture. The susceptor is present in an amount effective to allow the susceptor composition to be heated by RF energy. In a preferred embodiment, the susceptor also functions as an adhesive. The susceptor is an ionic or polar compound and acts as either a charge-carrying or an oscillating/vibrating component of the susceptor composition. The susceptor generates thermal energy in the presence of an RF electromagnetic or electrical field (hereafter RF field).

CROSS REFERENCE TO RELATED APPLICATION

[0001] The present application is a continuation-in-part of applicationSer. No. 09/404,200, filed Sep. 23, 1999, which is acontinuation-in-part of application Ser. No. 09/270,505, filed Mar. 17,1999, which claims the benefit of U.S. provisional application No.60/078,282, the contents of each of which are fully incorporated byreference herein.

[0002] This patent application is related to the following co-pendingU.S. utility patent application: “Radio Frequency Heating System,”-application Ser. No. 09/270,507, filed Mar. 17, 1999, the contents ofwhich are incorporated by reference herein.

BACKGROUND OF THE INVENTION

[0003] 1. Field of the Invention

[0004] This invention relates generally to the use of media containingionic compounds and/or nonionic compounds with high dipole moments as aradio frequency (RF) susceptors in RF activated systems.

[0005] 2. Related Art

[0006] Radio frequency (RF) heating is a well established non-contactprecision heating method that is used to generate heat directly withinRF susceptors, and indirectly within materials that are in thermallyconductive contact with RF susceptors. RF susceptors are materials thathave the ability to couple and convert RF energy into heat energy withinthe material.

[0007] Conventional adhesives are not suitable RF susceptors that can bedirectly heated and activated by RF heating. Rather, these conventionaladhesives are typically heated indirectly through thermally conductivecontact with an RF susceptor material. FIG. 1 illustrates twoconventional methods that are currently used in industry for indirect RFheating of conventional adhesives: The first method is illustrated inFIG. 1A, where susceptor material 102 exists as a bulk macroscopiclayer. RF susceptor material 102 is directly heated by RF energy, andadhesive layer 104 is indirectly heated through thermally conductivecontact with RF susceptor material 102. For example, adhesive layer 104may be applied to a continuous surface of susceptor material 102, suchas steel or aluminum. The second method is illustrated in FIG. 1B, wheresusceptor material 112 consists of discrete macroscopic particles.Adhesive layer 114 is loaded with macroscopic particles of a RFsusceptor material 112, such as macroscopic particles or flakes of metaloxides, metallic alloys, or aluminum. With this conventional method,each RF susceptor particle 112 acts as a discrete RF susceptor,generating heat throughout adhesive layer 114.

[0008] An example of a conventional RF energy activated composition,such as that shown in FIG. 1B, is described in U.S. Pat. No. 5,378,879,issued to Monovoukas (“Monovoukas”). Monovoukas utilizes macroscopic“loading particles” as discrete RF susceptors. The particles are heatedby RF energy and in turn conduct heat to the surroundings. Thesemacroscopic loading particles are thin flakes (i.e. in thin disk-likeconfiguration) that are designed to be admixed to relatively thickextruded materials. However, these flakes are not well suited for use assusceptors in thin film bonding applications in which physicaldistortions, discolorations in the surface, or opacity of the bondedfilms would result from the flakes.

[0009] Another example of a conventional inductively activated adhesiveis described in U.S. Pat. No. 3,574,031, issued to Heller et al.(“Heller”). Heller describes a method of heat welding thermoplasticbodies using an adhesive layer that contains uniformly dispersedmacroscopic RF susceptors, typically iron oxide particles. Thesediscrete RF susceptor particles are ferromagnetic in nature. Adisadvantage of this type of method is that a tradeoff must be madebetween the size of the particle employed versus the power level andduration of the inductive heating process. For example, if susceptorparticles are kept small in size, the mechanical strength of the bondtends to increase. However, as the size of these discrete susceptors isreduced, the power levels and dwell times required to heat the RFsusceptor material and achieve acceptable bonds tend to increase.Another disadvantage of this type of method is the high levels ofloading of the medium with RF susceptor particles that is required forefficient activation. Such high loading levels detract from the physicalproperties and rheology of the adhesive composition. Still anotherdisadvantage is the dark color and opacity of the composition, whichrenders the composition undesirable for many applications.

[0010] An example of adhesive activated by a dielectric process isdescribed in U.S. Pat. No. 5,661,201, issued to Degrand (“Degrand”).Degrand describes a thermoplastic film including at least one ethylenecopolymer and a sufficient quantity of N,N-ethylene-bisstearamide thatis capable of being sealed utilizing a current at a frequency of about27.12 megahertz (MHz). A disadvantage of this type of film and sealingprocess is the inherent tendency to also heat the adherand.

[0011] U.S. Pat. No. 5,182,134, issued to Sato, discloses methods ofcuring a thermoset composition by applying an RF signal having afrequency of about 1 to 100 MHz to a composition comprising a majorportion of a thermoset and a receptor. The receptor is described asbeing one of the alkali or alkaline earth metal sulfate salts (e.g.calcium sulfate), aluminum trihydrate, quaternary ammonium salts,phosphonate compounds, phosphate compounds, polystyrene sulfonate sodiumsalts or mixtures thereof. According to this patent, all of theexemplified compositions took longer than one second to heat.

[0012] U.S. Pat. No. 5,328,539, issued to Sato, discloses methods ofheating thermoplastic susceptor compositions by applying an RF signalhaving a frequency of about 1 to 100 MHz. The susceptors are describedas being one of the alkali or alkaline earth metal sulfate salts (e.g.calcium sulfate), aluminum trihydrate. quaternary ammonium salts,phosphonate compounds, phosphate compounds. polystyrene sulfonate sodiumsalts or mixtures thereof. According to this patent. all of theexemplified compositions took longer than one second to heat.

[0013] U.S. Pat. No. 4,360,607, issued to Thorsrud, discloses acomposition suitable for sensitizing thermoplastic compositions to theheating effects of microwave energy comprising (1) an alcohol amineor-derivative thereof, (2) a simple or polymeric alkylene glycol orderivative thereof, (3) silica and, optionally. (4) a plasticizer.

[0014] U.S. Pat. No. 5,098,962, issued to Bozich, discloses a waterdispersible hot melt adhesive composition comprising:

[0015] (a) from about 40% to 95% by weight of a water dispersibleionically substituted polyester resin having a molecular weight fromabout 10,000 to about 20,000 daltons;

[0016] (b) from about 60% to about 5% by weight of one or morecompatible plasticizers; and

[0017] (c) from about 0.1% to about 1.5% of one or more compatiblestabilizers of the anti-oxidant type.

[0018] Examples of plasticizers that may be used according to thispatent include one or more low molecular weight polyethylene glycols,one or more low molecular weight glycol ethers, glycerin, butyl benzylphthalate and mixtures thereof.

[0019] U.S. Pat. No. 5,750,605, issued to Blumenthal et al., discloses ahot melt adhesive composition comprising:

[0020] (i) 10 to 90% by weight of a sulfonated polyester condensationpolymer;

[0021] (ii) 0 to 80% by weight of a compatible tackifier;

[0022] (iii) 0 to 40% by weight of a compatible plasticizer;

[0023] (iv) 5 to 40% by weight of a compatible wax diluent with amolecular weight below 500 g/mole containing at least one polarfunctional group, said group being present at a concentration greaterthan 3×10⁻³ equivalents per gram;

[0024] (v) 0 to 60% by weight of a compatible crystalline thermoplasticpolymer; and

[0025] (vi) 0 to 3% by weight of a stabilizer.

[0026] What is needed is a composition (e.g. adhesive composition orcoating) containing either dissolved or finely dispersed susceptorconstituents that are preferably colorless or of low color. Further, thecomposition should be transparent or translucent throughout an adhesivematrix or plastic layer. This type of RF susceptor will result in moredirect and uniform heating throughout an adhesive matrix or plasticlayer. Further, it is desirable that such a composition will allowbonding with no physical distortion or discoloration in the bondedregion of thin films. Still another desirable feature is activation ofthe RF susceptors at frequencies, e.g. of about 15 MHz or below, mostpreferably about 13.5 MHz, which are more economical to generate thanhigher frequencies and do not substantially heat dielectric substrates.A further desirable feature is that the composition can be activated ormelted in less than one second and that it exhibit acceptable shearstrength. It is also desirable to have a formulation which may beoptimized for a particular application, such as cutting, coating, orbonding substrates.

SUMMARY OF THE INVENTION

[0027] The present invention generally relates to the creation and useof a composition (also referred to as a “susceptor composition”) thatcan bond two or more layers or substrates to one another and that can beused to coat or cut a substrate. The susceptor composition is activatedin the presence of radio frequency (RF) energy.

[0028] In one embodiment, the susceptor composition of the presentinvention comprises a susceptor and a carrier. The carrier and susceptorare blended with one another and form a mixture, preferably asubstantially uniform mixture. The susceptor is present in an amounteffective to allow the susceptor composition to be heated by RF energy.In a preferred embodiment, the susceptor also functions as an adhesiveor coating.

[0029] In another embodiment of the present invention, the susceptorcomposition further comprises an adhesive compound. The adhesivecompound, susceptor, and carrier are blended with one another to form amixture that is activated in the presence of RF energy. Preferably, themixture is substantially uniform.

[0030] In another embodiment of the present invention, the susceptorcomposition further comprises at least one of a thermoplastic polymer,thermoset resin, elastomer, plasticizer, filler or other material. Theadditive, susceptor, and carrier are blended with one another to form amixture that is activated in the presence of RF energy.

[0031] In yet another embodiment of the present invention, thecomposition can further comprise a second carrier that is an insolubleporous carrier that is saturated with the composition.

[0032] The susceptor is an ionic or polar compound and acts as either acharge-carrying or an oscillating/vibrating component of the susceptorcomposition. The susceptor generates thermal energy in the presence ofan RF electromagnetic or electrical field (hereafter RF field).According to the present invention, the susceptor can be an inorganicsalt (or its respective hydrate), such as stannous chloride (SnCl₂),zinc chloride (ZnCl₂) or other zinc salt, or lithium perchlorate(LiClO₄), or an organic salt, such as lithium acetate (LiC₂H₃O₂). Thesusceptor can be a non-ferromagnetic ionic salt. The susceptor can alsobe a polymeric ionic compound (“ionomer”) which preferably alsofunctions as an adhesive or coating. Under RF power levels of about 0.05kilowatt (kW) to 1 kW, and frequencies of about 1 to 100 MHz, thesusceptor composition of the present invention facilitates (a) thebonding of single layers of polymeric materials such as polyolefins,non-polyolefins, and non-polymeric materials, as well as multilayerstacks of these materials, and (b) coating on a substrate such as aprinted pattern on plastic films, metallic foils, etc.

[0033] Surprisingly, it has been discovered that when an ionomer iscombined with a polar carrier, much more heating occurs when exposed toRF energy than when the ionomer or carrier is exposed separately to RFenergy. Also surprisingly, it has been discovered that when the polarcarrier is present at about 13-30% weight percent, more preferably,about 15-25 weight percent, most preferably, about 20-23 weight percent,very short heating times are possible while retaining acceptable shearstrength of the bond.

[0034] According to another embodiment of the present invention, amethod of bonding a first material or substrate to a second material orsubstrate comprises interposing a composition according to the inventionbetween the first and second materials and applying RF energy to thecomposition to heat the composition, thereby causing the first andsecond materials to become bonded. In one embodiment, the compositioncomprises a susceptor and a carrier that are distributed in one anotherto form a mixture, preferably, a substantially uniform mixture.Optionally, the composition may further comprise other compounds andadditives as described herein. The susceptor is present in thecomposition in an amount effective to allow the composition to be heatedby RF energy.

[0035] According to another embodiment of the present invention, amethod of bonding or adhering a first substrate to a second substrateincludes: applying a first composition onto the first substrate;applying a second composition onto the second substrate; contacting thefirst composition with the second composition; applying RF energy to thefirst and second compositions to heat the compositions, thereby causingthe first and second substrates to become adhered or bonded; wherein oneof the compositions comprises a susceptor and the other of thesusceptors is a polar carrier, and the susceptor and/or the carrier arepresent in amounts effective to allow the first and second compositionsto be heated by RF energy.

[0036] According to yet another embodiment of the-present invention, amethod of bonding or adhering a first substrate to a second substrateincludes: applying a first composition onto the first substrate;applying a second composition onto the first composition; contacting thesecond substrate with the second composition; and applying RF energy tothe first and second compositions to heat the compositions, therebycausing the first and second substrates to become adhered or bonded,wherein one of the compositions comprises a susceptor and the other ofthe compositions is a polar carrier, and the susceptor and/or thecarrier are present in amounts effective to allow the first and secondcompositions to be heated by RF energy.

[0037] According to another embodiment of the present invention, amethod of making a susceptor composition comprises admixing a susceptorand a carrier, wherein, preferably, the carrier and susceptor aresubstantially uniformly dispersed in one another and form a uniformmixture. The susceptor and/or carrier are present in the composition inan amount effective to allow the susceptor composition to be heated byRF energy.

[0038] According to a further embodiment of the present invention, anadhered or a bonded composition can be obtained according to thedisclosed methods.

[0039] According to a further embodiment of the present invention, a kitfor bonding a first material to a second material comprises one or morecontainers, wherein a first container contains a composition comprisinga susceptor and a carrier that are dispersed in one another and form amixture. The kit may also contain an adhesive or elastomeric compound orother additives as disclosed herein. The susceptor and/or carrier arepresent in an amount effective to allow the composition to be heated byradio frequency energy.

[0040] According to a further embodiment of the present invention, a kitfor adhering or bonding a first substrate to a second substrate,comprises at least two containers, wherein one of the containerscomprises a susceptor and another of the containers comprises a polarcarrier, wherein when the susceptor and the carrier are applied tosubstrates and the susceptor and carrier are interfaced, a compositionis formed that is heatable by RF energy.

[0041] The invention also relates to a composition comprising anionomeric polymer and a polar carrier.

[0042] The invention also relates to a method of curing a thermosetresin, comprising combining the thermoset resin with a polar carrier togive a mixture and exposing the mixture to RF energy.

[0043] The invention relates to an apparatus, having: a first portionhaving a first mating surface; a second portion, having a second matingsurface; a composition disposed between the first mating surface and thesecond mating surface, wherein the composition comprises a susceptor anda polar carrier wherein the susceptor and/or the polar carrier arepresent in amounts effective to allow the composition to be heated by RFenergy, and wherein the composition adheres the first mating surface tothe second mating surface such that application of a force to separatethe first mating surface and the second mating surface results inbreakage of the apparatus unless the composition is in a melted state.

[0044] The invention also relates to a method of applying a protectivefilm or printed image/ink on a substrate.

[0045] The invention also relates to a method for dynamically bonding afirst adherand to a second adherand. The method includes: (1) creatingan article of manufacture comprising the first adherand, the secondadherand, and a composition, the composition being between the firstadherand and the second adherand, wherein the composition can beactivated in the presence of an RF field; (2) moving the article ofmanufacture along a predetermined path; (3) generating along a portionof the predetermined path an RF field having sufficient energy toactivate the composition, wherein the composition is activated by itsless than one second exposure to the RF field.

[0046] The invention also relates to a method for applying a susceptorcomposition to a substrate. In one embodiment, the method includes: (1)formulating the susceptor composition as a liquid dispersion; (2)applying the liquid dispersion of the susceptor composition to thesubstrate; (3) drying the susceptor composition, wherein the drying stepincludes the step of applying RF energy across the composition, therebygenerating heat within the liquid dispersion. In a preferred embodiment,one may roll up the substrate after the susceptor composition has dried.

[0047] The invention also relates to a method for cutting a substrate.The method includes: (1) applying a composition to a portion of thesubstrate, wherein the composition comprises a susceptor and polarcarrier wherein the susceptor and/or said polar carrier are present inamounts effective to allow the composition to be heated by RF energy,and wherein the portion of the substrate defines a first section of thesubstrate and a second section of the substrate; (2) melting the portionof the substrate by heating the composition via RF energy; and (3) afterthe portion of the substrate has begun to melt, applying a force to thesubstrate to separate the first section from the second section.

[0048] The method also relates to a method of dynamically bonding afirst substrate to a second substrate. The method including: applying acomposition onto the first substrate; after applying the compositiononto the first substrate, forming a roll of the first substrate; storingthe roll; unrolling the roll; and while unrolling the roll: joining anunrolled portion of the first substrate with a portion of the secondsubstrate such that the portion of the second substrate is in contactwith a portion of the composition applied onto the first substrate; andapplying RF energy to the portion of the composition, wherein theportion of the composition heats and melts as a result of the RF energybeing applied thereto.

[0049] Further features and advantages of the present invention, as wellas the structure and operation of various embodiments of the presentinvention, are described in detail below with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The present invention is described with reference to theaccompanying drawings. In the drawings, like reference numbers indicateidentical or functionally similar elements. Additionally, the left-mostdigit(s) of a reference number identifies the drawing in which thereference number first appears.

[0051]FIGS. 1A and 1B illustrate conventional schemes for inductivelyheating adhesives.

[0052]FIG. 2 shows an RF active composition according to the presentinvention.

[0053]FIG. 3 shows a susceptor composition placed between two polyolefinlayers to be attached according to the present invention.

[0054]FIG. 4 illustrates a block diagram of an RF heating systemaccording to a first embodiment.

[0055]FIG. 5 illustrates a block diagram of a heating system accordingto a second embodiment.

[0056]FIG. 6 illustrates a two probe heating system.

[0057]FIGS. 7A and 7B further illustrate the two probe heating system.

[0058]FIG. 7C illustrates a probe having a curled end to reduce coronaeffects.

[0059]FIG. 8 illustrates one embodiment of an alternating voltagesupply.

[0060]FIG. 9 is a flow chart illustrating a process for heating acomposition according to the present invention.

[0061]FIG. 10A further illustrates one embodiment of an impedancematching circuit.

[0062]FIG. 10B further illustrates another embodiment of an impedancematching circuit.

[0063]FIG. 11 shows a method of bonding adherents using a compositionthat is activated in the presence of RF energy.

[0064] FIGS. 12 to 17 illustrate additional embodiments of probes 602and 604.

[0065]FIG. 18 illustrates one embodiment of an application system forapplying a composition according to the present invention to asubstrate.

[0066]FIG. 19 illustrates one embodiment of a system for bonding oradhering various adherents.

[0067]FIGS. 20A and 20B illustrates a static bonding system for bondingadherents.

[0068]FIG. 20C illustrates an electrically insulating block for housingprobes.

[0069]FIG. 21 illustrates an in-line bonding system.

[0070]FIG. 22 further illustrates one embodiment of the in-line bondingsystem illustrated in FIG. 21.

[0071] FIGS. 23-27 illustrate alternative designs of the in-line bondingsystem illustrated in FIG. 21.

[0072]FIGS. 28A and 28B illustrate one embodiment of a system for themanufacture of flexible packaging material.

[0073]FIG. 29 further illustrates film 2815.

[0074]FIG. 30 illustrates one embodiment of film 2870.

[0075]FIG. 31 illustrates an alternative system for manufacturing an RFactivated adhesive film for use in the flexible packaging industry.

[0076]FIG. 32 illustrates a conventional aseptic package materialconstruction.

[0077]FIG. 33 illustrates an aseptic package material according to oneembodiment that does not include metallic foil.

[0078]FIG. 34 illustrates another embodiment of an aseptic packagingmaterial construction that does not use metallic foils.

[0079]FIG. 35 illustrates a conventional cap sealing construction.

[0080]FIG. 36 illustrates a seal, according to one embodiment, forsealing a bottle.

[0081]FIG. 37 illustrates a design for adhering a flexible bag to anouter box.

[0082]FIG. 38 illustrates a step and repeat manufacturing system.

[0083]FIG. 39 illustrates an index table bonding system.

[0084]FIG. 40 shows an example experimental set-up utilized to testcompositions according to the present invention.

[0085]FIG. 41 illustrates another experimental set-up for testingcompositions according to the present invention.

[0086]FIG. 42 illustrates test probes.

[0087]FIG. 43 illustrates a process for assembling a book, magazine, orperiodical, or the like.

[0088]FIG. 44 illustrates a paper substrate coated with a susceptorcomposition.

[0089]FIG. 45 illustrates a stack of coated paper substrates.

[0090]FIGS. 46 and 47 illustrates one embodiment of an envelope ormailer according to the present invention.

[0091]FIG. 48 illustrates a cross-section of a container sealed with asusceptor composition of the present invention.

[0092]FIG. 49 illustrates another example of a device sealed orotherwise joined together with a composition of the present invention.

[0093]FIG. 50 shows another example of a device sealed or otherwisejoined together with a composition of the present invention.

[0094]FIG. 51 illustrates still another example of a cross-section of acontainer 5100 that has been sealed with the adhesive of the presentinvention.

[0095]FIG. 52 illustrates a system for bonding two substrates.

[0096]FIG. 53 illustrates another embodiment of a system for bonding twosubstrates.

[0097]FIG. 54 depicts a graph showing RF activation time vs. % Glycerinfor a composition comprising AQ55S.

[0098]FIG. 55 depicts a graph showing shear holding time vs. % glycerinfor a composition comprising AQ55S.

[0099]FIG. 56 depicts a graph showing RF activation time vs. % glycerinfor a composition comprising AQ35S.

[0100]FIG. 57 depicts a graph showing shear holding time vs. % glycerinfor a composition comprising AQ35S.

[0101]FIG. 58 depicts a family of curves showing RF activation time vs.% various polar carriers.

[0102]FIG. 59 depicts a graph showing RF activation time vs. % PARICIN220 in a composition comprising 80% AQ55S/20% glycerin.

[0103]FIG. 60 depicts a graph showing brookfield viscosity vs. % PARICIN220 in a composition comprising 80% AQ55S/20% glycerin.

[0104]FIG. 61 depicts a graph showing RF activation time vs. % glycerinin a composition comprising the sodium salt of an ethylene acrylic acidcopolymer (MICHEM Prime 48525P).

[0105]FIG. 62 illustrates a seam sealing system according to oneembodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0106] I. Overview and Discussion of the Invention

[0107] II. Terminology

[0108] A. Sulfonated Polymers

[0109] B. Acrylic Acid and Maleic Anhydride Polymers and Copolymers

[0110] C. Starch/Polysaccharide Derivatives

[0111] D. Proteins

[0112] E. Others

[0113] III. The Polar Carrier

[0114] IV. Further Additives to the Susceptor Compositions

[0115] A. Adhesive/Thermoplastic Additives

[0116] B. Adhesive/Coating Thermoset Additives

[0117] C. Surfactant Additives

[0118] D. Plasticizer Additives

[0119] E. Tackifiers

[0120] F. Fillers

[0121] G. Stabilizers and Antioxidants

[0122] H. Other Additives

[0123] V. Applying the Susceptor Compositions to Substrates

[0124] VI. Apparatus For Activating the Various Compositions of thePresent Invention

[0125] VII. Method of Bonding Substrates

[0126] VIII. Additional Probe Embodiments

[0127] IX. Applicator System for Applying a Composition of the PresentInvention to a Substrate/Adherand

[0128] X. Systems for Adhering or Bonding two Adherands.

[0129] XI. Exemplary Specific Applications of the Present Invention

[0130] A. Manufacture of Flexible Packaging

[0131] B. Food Packaging and Cap Sealing

[0132] C. Printing Applications

[0133] D. Bookbinding and Mailers

[0134] E. Security Devices

[0135] F. Thermal Destruction

[0136] G. Seam Sealing

[0137] XII. Kits

[0138] XIII. Experimental Set-up

[0139] XIV. Examples

[0140] I. Overview and Discussion of the Invention

[0141] The present invention is directed towards an RF susceptorcomposition and methods and systems of bonding, cutting, and/or coatingsubstrates and surfaces using the susceptor composition. The susceptorcomposition is a mixture of RF susceptors and/or adhesive/coatingcompounds and/or other additives dissolved or finely dispersed in amatrix. Preferably, the RF susceptors and/or adhesive compounds and/orother additives are uniformly dissolved or finely dispersed in thematrix. The susceptor composition is capable of coupling efficiently inan RF field having a frequency of about 15 MHz or below. In order to beuseful in industry and commercial products, a susceptor compositionpreferably has the following characteristics: (1) an activation time inthe presence of a low power RF field on the order of 1 second or less,(2) adequate bond or adhesive strength for the intended use, (3)transparency or translucency and only slight coloration (if any), (4)minimal distortion of the substrates being attached, and (5) on demandbonding of preapplied adhesive. Further, it is desirable that thesusceptor composition have coupling ability in the absence of volatilesolvents, although the presence of nonvolatile liquids (such asplasticizers) may be desirable. These characteristics are important inproviding sufficient heat transfer to the substrates or layers to bebonded to one another, or for adhesion to take place at the interface.Additionally, the susceptor composition should not interfere with thethermal bonding or inherent adhesive properties of the substrates orlayers to be bonded or adhered to one another.

[0142] According to the present invention, a susceptor composition usedto bond or adhere substrates or layers can be directly heated byexposure to an RF field having frequencies ranging from 1-100 MHz. Thesusceptor composition comprises a susceptor, and a carrier blended withone another to form a mixture. In addition, the susceptor compositioncan further comprise one or more adhesive compounds blended with thesusceptor and carrier to form the mixture.

[0143] Susceptors are either ionic or polar compounds introduced as acomponent of a composition, such that RF heating of the resultingsusceptor composition occurs. An ionic susceptor is an ionic compoundintroduced as a sufficiently charge-carrying or oscillating component ofthe composition. A polar susceptor is a polar compound which hassufficiently high dipole moment that molecular oscillations orvibrations of the compound occur when exposed to an RF field. As shownin FIG. 2, a susceptor composition 202 comprises a continuous mixture ofsusceptors such as microscopic, ionic salts or polymeric ionic compoundsor dipoles 204, which generate thermal energy in the presence of the RFfield. It has been discovered that acceptable bonding results occur withinorganic salts such as stannous chloride (SnCl₂); zinc salts such aschloride (ZnCl₂), bromide (ZnBr₂) and the like; and lithium perchlorate(LiClO₄), and organic salts such as lithium acetate (LiC₂H₃O₂). Thesesalts or combination of salts, when distributed in the mixture, createan ionic and/or polar medium capable of being heated by RF energy.

[0144] II. Terminology

[0145] “RF Energy” means an alternating electromagnetic field having afrequency within the radio frequency spectrum.

[0146] A “susceptor composition” comprises a susceptor and a carrierinterfaced with one another and/or mixed or blended together.Preferably, the susceptor and carrier are mixed together. Morepreferably, the susceptor and carrier are substantially uniformly mixedtogether. In another embodiment, the susceptor and carrier areinterfaced together by disposing a layer of the susceptor onto a layerof the carrier or visa versa. In this embodiment, the susceptor may becoated onto a first substrate and the carrier, with or without addedingredients such as a wax or other additives that prevent the carrierfrom evaporating substantially, may be coated onto a second substrate.The first and second substrates containing the susceptor and carrierlayers, respectively, may then be brought into contact or interfaced andactivated then or at a later time.

[0147] The susceptor compositions of the invention may further compriseone or more adhesive compounds or other additives mixed, preferablysubstantially uniformly mixed, together with the susceptor and thecarrier. The susceptor composition is activated in the presence of radiofrequency (RF) energy. The susceptor composition can be used to bond twoor more layers or substrates to one another, can be used as a coating,and can be used to thermally cut substrates.

[0148] A “carrier” provides the mobile medium in which the susceptorsare dissolved, distributed, or dispersed. Preferably, the carrier is apolar carrier as defined below which enhances the activation of thecompositions. Carriers (also referred to as mobile media) can beliquids, such as solvents and plastisizers, or polymers that areutilized for their polar functionality and for their ability to beheated by RF energy.

[0149] An “adhesive compound” refers to polymers, copolymers and/orionomers as described herein that are blended into the susceptorcomposition to enhance its adhesive properties.

[0150] “Bonding” is defined as the joining of one substrate to anothersubstrate to cause a physical joining process to occur.

[0151] “Adhesion” is an interaction between two adherands at theirinterface such that they become attached or joined.

[0152] A “substantially transparent” mixture refers to a mixture thattransmits greater than about 50% of incident visible light.

[0153] “Thermal bonding” or “welding” is defined as the reflowing of onesubstrate into another substrate to cause a physical joining process tooccur.

[0154] “Mechanical bonding” occurs between adherands when a susceptorcomposition holds the adherands together by a mechanical interlockingaction.

[0155] An RF “susceptor” converts coupled RF energy into heat energy inthe susceptor composition. According to the present invention, thesusceptor, as described above, is either the charge carrying oroscillating ionic compound or the oscillating polar compound having asufficiently high dipole moment comprising a composition to generatethermal energy in the presence of an RF field. Generally, the susceptorcan be a salt. For example, the susceptor can be an inorganic salt orits respective hydrate(s), such as stannous chloride (SnCl₂). stannouschloride dihydrate (SnCl₂×2H₂O ), lithium perchlorate (LiClO₄), lithiumperchlorate trihydrate (LiClO₄×3H₂O ) or an organic salt, such as analkali metal salt of a C₁₋₄ alkanoic acid such as lithium acetate(LiC₂H₃O₂), lithium acetate dihydrate (LiC₂H₃O₂×2H₂O ), or sodiumacetate and the like; alkali metal salts of arylcarboxylic acids such aslithium benzoate, sodium benzoate, and the like; alkali metal salts ofalkyl and aryl sulfonates such-as sodium methylsulfonate and sodiump-toluenesulfonate and the like. Other types of salts and theirrespective hydrates include, but are not limited to, magnesium acetate,magnesium nitrate, sodium-based salts (such as sodium chloride, sodiumbromide and the like), lithium-based salts (such as lithium bromide,lithium carbonate, lithium chloride, etc.) and potassium-based salts.Many of these salts are commercially available from Aldrich ChemicalCompany, Milwaukee, Wis. See the Aldrich Catalog Handbook of FineChemicals 1996-1997. It is not intended that this list of salts is anexclusive or comprehensive list. These salts are disclosed as typicalexamples. The present invention is not restricted to the listed salts,as would be apparent to those of skill in the art.

[0156] The susceptor can also be an ionomer. Preferably, the ionomeralso functions as an adhesive and/or coating. Examples of such ionomersinclude without limitation styrenated ethylene-acrylic acid copolymer orits salts, sulfonated polyesters and their salts, sulfonated polystyreneand its salts and copolymers, polyacrylic acid and its salts andcopolymers, hydroxy/carboxylated vinylacetate-ethylene terpolymers,functionalized acrylics, polyesters, urethanes, epoxies, alkyds, latex,gelatin, soy protein, casein and other proteins, alginate, carrageenan,starch derivatives, ionic polysacharides, and the like. An example of anionomer that does not function as an adhesive is sodiumpolystyrenesulfonate.

[0157] Examples of ionomer adhesives are described in more detail below.

[0158] A. Sulfonated Polymers

[0159] Sulfonated polyesters and copolymers thereof are described inU.S. Pat. Nos. 5,750,605, 5,552,495, 5,543,488, 5,527,655, 5,523,344,5,281,630, 4,598,142, 4,037,777, 3,033,827, 3,033,826, 3,033,822,3,075,952, 2,901,466, 2,465,319, 5,098,962, 4,990,593, 4,973,656,4,910,292, 4,525,524, 4,408,532, 4,304,901, 4,257,928, 4,233,196,4,110,284, 4,052,368, 3,879,450, and 3,018,272. The invention relates tocompositions comprising sulfonated polyesters and copolymers thereof,e.g. as described in these patents, together with a polar carrier asdescribed herein as well as the adhesive compositions described in thesepatents (comprising the sulfonated polyesters and copolymers thereof)together with the polar carrier. Such sulfonated polyesters andcopolymers thereof are one preferred embodiment of the presentinvention, as such materials function both as an ionomeric susceptor andas an adhesive.

[0160] In a preferred embodiment, the sulfonated polyester is a higherTg (about 48° C. to about 55° C. or higher) linear polyester which showsimproved heat resistance compared to lower Tg (about 35° C.) linear orbranched sulfonated polyesters. Once blended with the polar carrier, theTg of the resulting composition should be higher than the temperature atthe intended use, e.g. higher than body temperature for diaperadhesives. For example, a linear sulfonated polyester with a Tg of 55°C. (e.g. AQ55S) blended with a sufficient amount (greater than 10%) ofpolar carrier (e.g. glycerin) to achieve RF activity will result in a Tghigher than body temperature if the polar carrier is no more than about35% of the composition.

[0161] In another embodiment, a salt comprising a sulfonated polyesterand a cationic dye as described in U.S. Pat. No. 5,240,780, areemployed. Such salts provide a colored susceptor composition that may beused, e.g. in printing.

[0162] Sulfonated polyesters may be prepared by the polycondensation ofthe following reactants:

[0163] (a) at least one dicarboxylic acid;

[0164] (b) at least one glycol;

[0165] (c) at least one difunctional sulfomonomer containing at leastone metal sulfonate group attached to an aromatic nucleus wherein thefunctional groups may be hydroxy, carboxyl, or amino groups.

[0166] The dicarboxylic acid component of the sulfonated polyesterscomprises aliphatic dicarboxylic acids, alicyclic dicarboxylic acids,aromatic dicarboxylic acids, or mixtures of two or more of these acids.Examples of such dicarboxylic acids include oxalic; malonic;dimethylmalonic; succinic; glutaric; adipic; trimethyladipic; pimelic;2,2-dimethylglutaric; azelaic; sebacic; fumaric; maleic; itaconic;1,3-cyclopentanedicarboxlyic; 1,2-cyclohexanedicarboxylic;1,3-cyclohexanedicarboxylic; 1,4-cyclohexanedicarboxylic; phthalic;terephthalic; isophthalic; 2,5-norbornanedicarboxylic; 1,4-naphthalic;diphenic; 4,4′-oxydibenzoic; diglycolic; thiodpropionic;4,4′-sulfonyldibenzoic; and 2,5-naphthalenedicarboxylic acids. Ifterephthalic acid is used as the dicarboxylic acid component of thepolyester, at least 5 mole percent of one of the other acids listedabove may also be used.

[0167] It should be understood that use of the corresponding acidanhydrides, esters, and acid chlorides of these acids is included in theterm “dicarboxylic acid. ” Examples of these esters include dimethyl1,4-cyclohexanedicarboxylate; dimethyl 2,5-naphthalenedicarboxylate;dibutyl, 4,4′-sulfonyldibenzoate; dimethyl isophthalate; dimethylterephathalate; and diphenyl terephthalate. Copolyesters may be preparedfrom two or more of the above dicarboxylic acids or derivatives thereof.

[0168] Examples of suitable glycols include poly(ethylene glycols) suchas diethylene glycol, triethylene glycol, tetraethylene glycol, andpentaethylene, hexaethylene, heptaethylene, octaethylene, nonaethylene,and decaethylene glycols, and mixtures thereof. Preferably thepoly(ethylene glycol) employed in the present invention is diethyleneglycol or triethylene glycol or mixtures thereof. The remaining portionof the glycol component may consist of aliphatic, alicyclic, and aralkylglycols Examples of these glycols include ethylene glycol; propyleneglycol; 1,3-propanediol; 2,4-dimethyl-2-ethylhexane-1,3,diol;2,2-dimethyl-1,3-propanediol; 2-ethyl-2-butyl-1,3-propanediol;2-ethyl-2-isobutyl-1,3-propanediol; 1,3-butanediol; 1,4-butanediol;1,5-pentanediol; 1,6-hexanediol; 2,2-4-trimethyl-1,6-hexanediol;thiodiethanol; 1,2-cyclohexanedimethanol; 1,3-cyclohexanedimethanol;1,4-cyclohexanedimethanol; 2,2,4,4-tetramethyl-1,3-cyclobutanediol;p-xylylenediol. Copolymers may be prepared from two or more of the aboveglycols.

[0169] The difunctional sulfo-monomer component of the sulfonatedpolyester may advantageously be a dicarboxylic acid or an ester thereofcontaining a metal sulfonate group or a glycol containing a metalsulfonate group or a hydroxy acid containing metal sulfonate group.

[0170] Advantageous difunctional sulfo-monomer components are thosewherein the sulfonate salt group is attached to an aromatic acid nucleussuch as benzene, naphthalene, diphenyl, oxydiphenyl, sulfonyldiphenyl,or methylenediphenyl nucleus. Particular examples include sulfophthalicacid, sulfoterephthalic acid, sulfoisophthalic acid,4-sulfonaphthalene-2,7-dicarboxylic acid, and their esters;metalosulfoaryl sulfonate having the general formula.

[0171] wherein X is a trivalent aromatic radical derived from asubstituted or unsubstituted aromatic hydrocarbon, Y is a divalentaromatic radical derived from a substituted or unsubstituted aromatichydrocarbon, A and B are carboalkoxy groups containing 1 to 4 carbonatoms in the alkyl portion or a carboxy group, the metal ion M is Li⁻,Na⁺, K⁺, Mg⁺⁺, Ca⁺⁺, Ba⁺⁻, Cu⁻⁺, Fe⁺⁺, Fe⁺⁻⁻ and n is 1 for monovalent Mor 2 for divalent M or 3 for trivalent M. When a monovalent alkali metalion is used, the resulting sulfonated polyesters are less readilydissipated by cold water and more rapidly dissipated by hot water. Whena divalent or a trivalent metal ion is used, the resulting sulfonatedpolyesters are not ordinarily easily dissipated by cold water, but aremore readily dissipated in hot water. Depending on the end use of thepolymer, either of the different sets of properties may be desirable. Itis possible to prepare the sulfonated polyester using, for example, asodium sulfonate salt and later by ion-exchange replace this ion with adifferent ion, for example, calcium, and thus alter the characteristicsof the polymer. In general, this procedure is superior to preparing thepolymer with divalent metal salt inasmuch as the sodium salts may bemore soluble in the polymer manufacturing components than are thedivalent metal salts. Polymers containing divalent or trivalent metalions are less elastic and rubber-like than polymers containingmonovalent ions. One such metallosulfoaryl sulfonate component may beprepared as shown by the following general reactions:

[0172] and other chlorinating agents (e.g., thionyl chloride, phosphorustrichloride, phosphorous oxychloride) may be used. In addition, thereaction between the sulfonyl chloride and the sulfophenol may becarried out in water or an inert organic solvent, and the base used maybe an alkali metal hydroxide or a tertiary amine. Such suitablecompounds are disclosed in U.S. Pat. No. 3,734,874.

[0173] Optionally, the polycondensation reaction may be carried out inthe presence of one or more of the following:

[0174] (d) an unsaturated mono- or dicarboxylic acid; and,

[0175] (e) a difunctional hydroxycarboxylic acid having one —CH₂—OHgroup. an aminocarboxylic acid having one —NRH group, an amino alcoholhaving one —CR₂—CH and one —NRH group, a diamine having two —NRH groups,or a mixture thereof, wherein each R is hydrogen or a C₁₋₄ alkyl group.

[0176] The α,β-unsaturated acids (d) are described by the followingstructure:

R—CH═CH—R¹

[0177] wherein R is H, alkylcarboxy, or arylcarboxy and R¹ is carboxy orarylcarboxy. Polymers derived from the above components can be used incombination with polymers derived from other components and/or incombination with other ethylenically unsaturated comonomers (e.g.,acrylic acid, acrylamide, butyl acrylate, diacetone acrylamide). Thecomonomers can be from 1-75 parts by weight, preferably 5-25 parts byweight α,β-unsaturated acids.

[0178] Advantageous difunctional components which are aminoalchoholsinclude aromatic, aliphatic, heterocyclic and other types as in regardto component (e). Specific examples include5-aminopentanol-1,4-aminomethylcyclo-hexanemethanol,5-amino-2-ethyl-pentanol-1,2-(4-β-hydroxyethoxyphenyl)-1-aminoethane,3-amino-2,2-dimethylpropanol, hydroxyethylamine, etc. Generally theseaminoalcohols contain from 2 to 20 carbon atoms, one —NRH group and one—CR₂—OH group.

[0179] Such difunctional monomer components which are aminocarboxylicacids include aromatic, aliphatic, heterocylic, and other types as inregard to component (c) and include lactams. Specific examples include6-aminocaproic acid, its lactam known as caprolactam,omegaaminoundecanoic acid, 3-amino-2-dimethylpropionic acid,4-(β-aminoethyl)benzoic acid, 2-(β-aminopropoxy)benzoic acid,4-aminomethylcyclohexanecarboxylic acid,2-(β-aminopropoxy)cyclohexanecarboxylic acid, etc. Generally thesecompounds contain from 2 to 20 carbon atoms.

[0180] Examples of such difunctional monomer component (e) which arediamines include ethylenediamine; hexamethylenediamine;2,2,4-trimethylhexamethylenediamine; 4-oxaheptane-1,7-diamine;4,7-dioxadecane-1,10-diamine; 1,4-cyclohexanebismethylamine;1,3-cycloheptamethylene-diamine; dodecamethylenediamine, etc.

[0181] Greater dissipatability is achieved when the difunctionalsulfo-monomer constitutes from about 6 mole percent to about 25 molepercent out of a total of 200 mole percent of (a), (b), (c), (d), andany (e) components of the polyester or polyesteramide. The total of 200mole percent can also be referred to as 200 mole parts.

[0182] Any of the above-identified difunctional monomers generallycontain hydrocarbon moieties having from 1 to about 40 carbon atoms inaddition to their two functional groups, but they may in general alsocontain up to six non-functional groups such as —O—, —S—, —SO₂—,—SO₂—O—, etc. For example, the poly(ethylene glycol) monomer used maycontain from 1 to about 19 oxy groups, such as -O— groups.

[0183] In a preferred embodiment, the ionomer is one of the sulfonatedpolyesters sold by Eastman Chemical Company, Kingsport, Tenn. (hereafter“Eastman”). which are water dispersible, linear or branched polyestersformed by the polycondensation of glycols with dicarboxylic acids, someof which contain sodiosulfo groups. Sulfopolyester hybrids may also beemployed which are formed by the in situ polymerization of vinyl and/oracrylic monomers in water dispersions of SULFOPOLYESTER. Such Eastmansulfonated polyesters may be purchased from Eastman under nos. AQ1045,AQ1350, AQ1950, AQ14000, AQ35S, AQ38S, AQ55S and EASTEK 1300.

[0184] The sulfonated polyesters and copolymers thereof may range fromabout 10 to about 90 weight percent, more preferably, about 60 to 80weight percent, most preferably about 70 weight percent of the totalcomposition. The polar carrier may range from about 10 to about 90weight percent, more preferably, about 20 to about 40 weight percent,most preferably, about 30 weight percent of the total composition. Theremainder of the composition may comprise one or more of the otheradditives described herein.

[0185] Compositions comprising branched sulfonated polyesters tend togive clear, tacky and flexible films. Compositions comprising linearpolyesters tend to give clear or white, tack-free, flexible films.

[0186] Other sulfonated polymers that can be used in the practice of theinvention include polystyrene sulfonate, acrylaminopropane sulfonate(AMPS) based polymers (e.g. 2-acrylamido-2-methylpropanesulfonic acidand its sodium salt available from Lubrizol Process Chemicals). Inaddition, urethane ionomers can be prepared by reacting a diisocyanatewith a diol that has sulfonate functionality (e.g. butane diolsulfonate).

[0187] B. Acrylic Acid and Maleic Anhydride Polymers and Copolymers

[0188] Other ionomers include acrylic acid polymers and copolymers andsalts thereof. Such polymers and copolymers are described in U.S. Pat.Nos. 5,821,294, 5,717,015, 5,719,244, 5,670,566, 5,618,876, 5,532,300,5,530,056, 5,519,072, 5,371,133, 5,319,020, 5,037,700, 4,713,263,4,696,951, 4.692,366, 4,617,343, 4,948,822, and 4,278,578.

[0189] The invention relates to compositions comprising the acrylic acidpolymers and copolymers thereof described in these patents together witha polar carrier as described herein as well as the adhesive compositionsdescribed in these patents (comprising the acrylic acid polymers andcopolymers thereof) together with the polar carrier.

[0190] Specific examples of such acrylic acid copolymers includeethylene acrylic acid copolymer and the ammonium (MICHEM 4983P) andsodium (MICHEM 48525P) salts thereof available from MichelmanIncorporated, Cincinnati, Ohio. A further example is vinyl acetateacrylic copolymers (e.g. ROVACE HP3442) available from Rohm and Hass,Philadelphia, Pa.

[0191] The acrylic acid polymers and copolymers may range from about 10to about 90 weight percent, more preferably, about 40 to 80 weightpercent, most preferably about 50-70 weight percent of the totalcomposition. The polar carrier may range from about 10 to about 90weight percent, more preferably, about 10 to about 40 weight percent,most preferably, about 30 weight percent of the total composition. Theremainder of the composition may comprise one or more of the otheradditives described herein.

[0192] Compositions comprising ethylene acrylic acid copolymers and apolar carrier tend to give clear, colorless, tack-free films with verygood adhesion that heat in well under one second when exposed to RF.Vinyl acetate acrylic copolymer compositions tend to give clear,colorless, flexible but very tacky films with very good adhesion thatheat in well under one second when exposed to RF.

[0193] In a preferred embodiment, compositions comprising acrylic acidpolymers or coplymers are applied as liquid dispersions and dried intoan RF susceptive coating.

[0194] Alternatively, maleic anhydride based copolymers such styrenemaleic anhydride, ethylene maleic anhydride, and popylene maleicanhydride (availbe from Eastman Chemicals) may be employed as anionomer. Such compositions are preferably applied as an aqueousdispersion at room temperature and dried into an RF susceptive coating.

[0195] C. Starch/Polysaccharide Derivatives

[0196] Other ionomers include starch and polysaccharide derivatives suchas polysulfonated or polysulfated derivatives, including dextransulfate, pentosan polysulfate, heparin, heparan sulfate, dermatansulfate, chondroitin sulfate, a proteoglycan and the like. Dextransulfate is available from Sigma Chemical Corporation, St. Louis, Mo.,with molecular weights of 10,000, 8,000 and 5,000. Examples of otherionic polysaccharides include carrageenan, chitosan, xanthan gum, etc.

[0197] Phosphorylated starch as disclosed in U.S. Pat. No. 5,329,004 maybe employed as a susceptor.

[0198] The starch/polysaccharide derivatives may range from about 10 toabout 90 weight percent, more preferably, about 60 to 80 weight percent,most preferably about 70 weight percent of the total composition. Thepolar carrier may range from about 10 to about 90 weight percent, morepreferably, about 20 to about 40 weight percent, most preferably, about30 weight percent of the total composition. The remainder of thecomposition may comprise one or more of the other additives describedherein.

[0199] D. Proteins

[0200] Other ionomers include proteins such as gelatin, soy protein,casein, etc. Gelatin is the purified protein derived from the selectivehydrolysis if collagen. Collagen is the principal organic component ofthe bones and skin of mammals. Common raw materials include bones,cattle hides and pigskins. Gelatins are classified as either acid type(A type) or limed (B type) according to the process by which they aremade. Particular examples of gelatins include KNOX gelatin as well astypes P, D, D-I, LB, LM and K, available from PB Gelatins. See also thegelatin described in U.S. Pat. No. 5,877,287. In a preferred embodiment,the gelatin is 45Y56-853-3V0-6CS, available from Eastman Gelatin,Peabody, Mass. Alternatively, a gelatin-modified polyurethane asdisclosed in U.S. Pat. No. 5,948,857 may be used.

[0201] In a preferred embodiment, the pH of the gelatin is raised orlowered in order to enhance the ionomeric character of the gelatin. ThepH may be raised by the addition of aqueous base to an aqueous solutionor suspension of the gelatin. Examples of suitable bases include alkalimetal hydroxides, alkali metal carbonates and bicarbonates, alkali metalacetates, ammonia, amino compounds such as methylamine, dimethylamine,trimethylamine, triethylamine, and the like. Alternatively, a basicbuffer solution may be added, e.g. a solution comprising2-amino-2-methyl-1-propanol; or a glycine buffer at pH 9.4 and 10.4;each of which is available from Sigma Chemical Corporation, St. Louis,Mo. Other buffers include 0.01 borax (pH 9.2), TRIS (pH 7-9.1 dependingon concentration), 0.05 M carbonate (pH 9.93), and 0.05 M trisodiumphosphate (pH 12). See “The Chemist's Companion,” A. J. Gordon and R. A.Ford, John Wiley & Sons, New York, N.Y., 1972. The pH may be lowered bythe addition of an acid such as HCl, HBr, H₂SO₄, H₃PO₄, or an organicacid such as C₁₋₄ alkanoic acid (e.g. acetic acid, propionic acid orbutyric acid), an arylcarboxylic acid (e.g. benzoic acid), orarylsulfonic acid (e.g.p-toluenesulfonic acid). Alternatively, an acidicbuffer may be added, e.g. acetate buffer at pH 4.5, 4.9 and 5.0; citratebuffer at pH 4.8; or a phosphate-citrate buffer at pH 5.0; each of whichis available from Sigma Chemical Corporation. Other buffers include0.005 M potassium tetraoxalate (pH 1.7), saturated potassium tartrate(pH 3.6), 0.05 M potassium phthalate (pH 4.0), and 0.05 M sodiumsuccinate (pH 5.3). See “The Chemist's Companion,” A. J. Gordon and R.A. Ford, John Wiley & Sons, New York. N.Y., 1972. As discussed in theExamples, it has been discovered unexpectedly that when the pH of thegelatin composition is shifted into the acidic or basic range, thecomposition exhibits enhanced heating in an RF field compared to theuntreated gelatin. The best heating occurs when the pH is low. Suchgelatin compositions give flexible films that attach well to substratesand heat in under one second.

[0202] In a preferred embodiment, the pH of the gelatin may range fromabout 8 to about 12. In a most preferred embodiment, the pH of thegelatin is about 10. In another preferred embodiment, the pH of thegelatin may range from about 1 to about 6. In a most preferredembodiment, the pH of the gelatin is about 2.

[0203] The gelatin may range from about 10 to about 90 weight percent,more preferably, about 60 to 80 weight percent, most preferably about 70weight percent of the total composition. The polar carrier may rangefrom about 10 to about 90 weight percent, more preferably, about 20 toabout 40 weight percent, most preferably, about 30 weight percent of thetotal composition. The remainder of the composition may comprise one ormore of the other-additives described herein.

[0204] E. Others

[0205] Other ionomers that may be used in the practice of the inventioninclude sulfonated novolak resins obtained by a process comprisingreacting an aromatic compound with a sulfonated agent to form asulfonated aromatic compound, condensing the sulfonated aromaticcompound with a non-sulfonated phenolic compound and an aldehyde oraldehyde precursor to form a sulfonated condensate, and reacting thecondensate with a monovalent or divalent metal oxide, hydroxide,carbonic acid, boronic acid or carboxylic acid. See U.S. Pat. No.5,098,774. Other ionomers that can be used are lignosulfonates and theirsodium salts which are available with different molecular weightsand-levels of sulfonation from Westvaco, North Charleson, S.C.

[0206] In addition, urethane ionomers can be prepared by reacting adiisocyanate with a diol that has carboxy functionality (e.g.dimethylol).

[0207] III. The Polar Carrier

[0208] In a preferred embodiment, the ionomer is combined with a carrierthat is a flowable polar compound, such as a polar solvent, having ahigh dielectric constant, e.g. ε (20° C.)≧ about 10, more preferably, ≧about 20. A preferred dielectric constant range is about 13-63 (25° C.),more preferably, about 17-43 (25° C.). It has been unexpectedlydiscovered that compositions comprising an ionomer and such a carrierheat much more rapidly when exposed to RF energy, even at low levels,compared to when the ionomer or carrier are exposed separately. Withoutbeing bound by any particular theory, it is believed that upon exposureto RF energy, the polar carrier allows for the migration and/orvibration of protons or metal ions from the ionomer, resulting in thegeneration of heat.

[0209] Such polar carriers include, but are not limited to, water,dimethylformamide (DMF), dimethylacetamide (DMAC), dimethylsulfoxide(DMSO), tetrahydrofuran (THF), polypropylene carbonates, ketones (suchas acetone, acetyl acetone, cyclohexanone, diacetone alcohol, andisophorone), alcohols (such as ethanol, propanol, 2-methyl-1-propanol,and the like) amino alcohols (such as ethanolamine), oxazolidines,polyols, organic acids (such as formic, acetic, propionic, butyric anddimethylol butyric acid and the like), anhydrides (such as aceticanhydride and maleic anhydride), amides (such as formamide, acetamideand propionamide), nitrites (such as acetonitrile and propionitrile),and nitro compounds (such as nitrobenzene, nitroaniline, nitrotoluene,nitroglycerine and any of the nitroparaffins). Any polar carrier thatcan weaken, to some degree, the ionic interaction between the anion andcation of the ionic susceptor, even if the susceptor component is anon-ionic compound, may be utilized in the present invention. Preferredpolar carriers are humectants (e.g., glycerin, 1,2-propanediol andpolyethyleneglycol), i.e., they retain at least a low level of moistureafter application. It is believed that the low level of residualmoisture enhances the RF activation of the compositions.

[0210] Examples of polyols that may be used as a polar carrier includeglycols such as diethylene glycol, triethylene glycol, tetraethyleneglycol, dipropylene glycol, thioethylene glycol, and pentaethylene,hexaethylene, heptaethylene, octaethylene, nonaethylene, anddecaethylene glycols, and mixtures thereof, as well as aliphatic,alicyclic, and aralkyl glycols. Particular examples of these glycolsinclude ethylene glycol; 1,2-propylene glycol; 1,3-propanediol;2,4-dimethyl-2-ethylhexane-1,3,diol; 2,2-dimethyl-1,3-propanediol;2-ethyl-2-butyl-1,3-propanediol; 2-ethyl-2-isobutyl-1,3-propanediol;1,3-butanediol; 1,4-butanediol; 1,5-pentanediol; 1,6-hexanediol;2,2-4-trimethyl-1,6-hexanediol; thiodiethanol;1,2-cyclohexanedimethanol; 1,3-cyclohexanedimethanol;1,4-cyclohexanedimethanol; 2,2,4,4-tetramethyl-1,3-cyclobutanediol;p-xylylenediol. Also included are polyethylene glycols, e.g. havingweight average molecular weights ranging from about 400 to about 2,000;mixed poly(ethylene)-poly(propylene) glycols having weight averagemolecular weights ranging up to about 6,000 and containing from about 30to about 90 weight percent ethylene oxide; the monomethyl, monoethyl andmonobutyl ethers of ethylene glycol, propylene glycol and diethyleneglycol, the monomethyl and monoethyl ethers of triethylene glycol; thedimethyl and diethyl ethers of diethylene glycol, dipropylene glycol andtrimethylene glycol. Examples of polyols containing three or morehydroxy groups include glycerin and derivatives of glycerin such asglycerol mono-, di-, and triacetate, or monomethacrylate. Also includedis polyvinylalcohol, which also functions as an adhesive compound.Polyvinylalcohols of molecular weights89,000-98,000,85,000-146,000,124,000-186,000, 31,000-50,000,85,000-146,000, 124,000-186,000, 13,000-23,000. 50,000-85,000, withvarious levels of hydrolysis, are available from Aldrich ChemicalCompany.

[0211] The polar carrier may also be an alkanolamine and substitutedalkanolamine based on ethanol and isopropanol such as mono-, di- andtriethanolamine, mono-, di- and triisopropanolamine, methylethanolamine,dibutylethanolamine, phenyldiethanolamine,di-(2-ethylhexyl)ethanolamine, dimethylisopropanolamine,dibutylisopropanolamine, and the like as well as mixtures thereof.

[0212] N-Alkyl sulfonamides are also useful carriers.

[0213] The present invention is not restricted to the listed carriers,and mixtures of carriers may be utilized, as would be apparent to thoseof skill in the art. Such polar carriers may comprise about 10 to 90weight percent of the composition. In a preferred embodiment, the polarcarrier comprises about 30 weight percent of the total composition. In amore preferred embodiment, the polar carrier comprises about 13-30%weight percent, more preferably, about 15-25 weight percent, mostpreferably, about 20-23 weight percent. At these percentages, very shortheating times are possible while retaining acceptable shear strength ofthe bond.

[0214] Preferable high dielectric constant carriers are those that cangenerate heat without being highly volatile, in order to preserve RFsusceptor mobility in the composition. Preferred carriers are glycolssuch as glycerine and N-methyl pyrrolidone (NMP). NMP has a high dipolemoment of 4.09 Debye, which produces a dielectric constant, K, of 32.2at 25° C. NMP is noncorrosive, biodegradable, and almost odorless. NMPhas a low order of oral toxicity and is neither a skin irritant nor asensitizer. NMP is also an excellent solvent both for a wide range oforganic compounds and polymers, as well as for some inorganic salts. Inshort, it is a very useful medium for dissolving or dispersingsusceptors and film formers that are employed in the bonding or adheringof substrates or layers according to the present invention.

[0215] A farther preferred high dielectric constant carrier isglycerine. Glycerine has a dielectric constant of 42.5 at 25° C., isnoncorrosive, biodegradable, and odorless. Glycerine is nontoxic and isneither a skin irritant nor a sensitizer. Thus, glycerine is a preferredcarrier for consumer products containing adhesives and coatings.Glycerine is also an excellent solvent both for a wide range of organiccompounds and polymers, as well as for some inorganic salts.

[0216] A suitable susceptor composition according to the presentinvention comprises a susceptor present in a concentration of from about10% to about 50% and a carrier present in a concentration of from about1% to about 75%. Additionally, another suitable susceptor compositionfurther comprises an adhesive compound or other additive as describedherein present in a concentration of from about 10% to about 35%. Thesusceptor composition can be used to bond or adhere substrates or layersto one another. The substrates can include single layers of polyolefinsand non-polyolefins, as well as multilayer stacks. Such stacks maycomprise 2, 3, 4, 5 or more layers. One or more susceptor compositions,which may be the same or different, may be between 2 or more layers ofthe multilayer stacks. All composition concentrations described hereincorrespond to weight-weight percentages, unless indicated otherwise.

[0217] IV. Further Additives to the Susceptor Compositions

[0218] A number of different additives may be added to the susceptorcompositions of the present invention including the carrier or mobilemedium. In order to provide uniform heating of a susceptor composition,the susceptors are dissolved, distributed, or dispersed, preferablysubstantially uniformly, in a carrier containing either various polymersand/or solvents or plastisizers. Some carriers, such as solvents,plastisizers, or polymers, are utilized for their polar functionalityand for their ability to enhance the heating process.

[0219] A. Adhesive/Thermoplastic Additives

[0220] The adhesive properties of the susceptor composition of thepresent invention are enhanced by the presence of one or morethermoplastic or adhesive compounds, such as polymers or copolymers,that are blended in the susceptor composition. Some of the thermoplasticor adhesive compounds utilized in the present invention include, but arenot limited to, polyesters such as a thermoplastic methylol polyesterprepared from the reaction of at least one dicarboxylic acid with adiglycidyl ether, a diglycidyl ester or combination thereof (see U.S.Pat. No. 5,583,187) or a cyanoacrylate/polyester adhesive composition(see U.S. Pat. No. 5,340,873); polyamides; polyurethanes (see U.S. Pat.No. 5,391,602); polysiloxanes; elastomers; polyvinylpyrrolidone;ethylene vinyl acetate copolymers (see U.S. Pat. No. 4,460,728),vinylpyrrolidone vinyl acetate copolymers; vinyl ether copolymers (e.g.polyvinyl methyl ether); polyvinyl alcohol; partially hydrolyzedpolyvinyl acetate; copolymers comprising a starch ester (see U.S. Pat.No. 5,498,224) and starch hydrolysates (see U.S. Pat. No. 5,827,553);graft copolymer prepared from a vinyl monomer and a polyalkylene oxidepolymer, and a hydroxy-containing ester or acid wax (see U.S. Pat. No.5,852,080); copolymers comprising a graft copolymer prepared from avinyl monomer, at least one polyalkylene oxide polymer, a polar wax andother optional ingredients (see U.S. Pat. No. 5,453,144); thermoplasticblock copolymers comprising an aromatic vinyl copolymer block, a dienepolymer or hydrogenated derivative thereof and other additives (see U.S.Pat. No. 5,723,222); vinyl chloride copolymers; vinylidene chloridecopolymers; vinylidene fluoride copolymers; vinyl pyrrolidone homo- andcopolymers; vinyl pyridine homo- and copolymers; hydrolyzed polyvinylalcohol and compositions thereof (see U.S. Pat. No. 5,434,216);cellulose esters (e.g. cellulose acetate and starch acetate, see U.S.Pat. No. 5,360,845) and ethers (e.g. hydroxypropyl cellulose, methylcellulose, ethyl cellulose, propyl cellulose and the like; see U.S. Pat.No. 5,575,840, 5,456,936 and 5,356,963); modified starch estercontaining adhesives (see U.S. Pat. No. 5,360,845); high amylose starchcontaining adhesive (see U.S. Pat. No. 5,405,437);poly-alpha olefins;propylene homo- and copolymers; ethylene homo- and copolymers(especially those of vinyl acetate, vinyl alcohol, ethyl- andbutyl-acrylate, carbon monoxide, acrylic and methacrylic acid, crotonicacid, and maleic anhydride), an alkyl acrylate hot melt adhesive (seeU.S. Pat. No. 4,588,767), a hot melt adhesive comprising an alkylacrylate and an alpha-olefin (see U.S. Pat. No. 4,535,140), a hot meltadhesive comprising an ethylene n-butyl acrylate copolymer (see U.S.Pat. No. 5,331,033), a hot melt adhesive comprising a graft copolymercomprising at least one vinyl monomer and at least one polyalkyleneoxide polymer (see U.S. Pat. No. 5,217,798), a vinyl acetate copolymercopolymerized with a cyclic ureido compound (see U.S. Pat. No.5,208,285), a hydrophilic polycarbodiimide (see U.S. Pat. No.5,100,994), a photopolymerized, pressure sensitive adhesive comprisingan alkyl acrylate, a monethylenically unsaturated polar copolymerizablemonomer, ethylene vinylacetate copolymer and a photo initiator (see U.S.Pat. No. 5,079,047), a hot melt adhesive comprising tackifying resins,oil diluent, and a substantially radial styrene-butadiene blockcopolymer (U.S. Pat. No. 4,944,993), an adhesive prepared from the vinylester of an alkanoic acid, ethylene, a dialkyl maleate, an N-methylolcomonomer, and an ethylenically unsaturated mono- or dicarboxylic acid(see U.S. Pat. No. 4,911,960), an adhesive prepared from the vinyl esterof an alkenoic acid, ethylene, a dialkyl maleate, and a monocarboxylicacid (see U.S. Pat. No. 4,892,917), a hot melt adhesive consistingessentially of an ethylene n-butyl acrylate copolymer (U.S. Pat. No.4,874,804), hot melt adhesive compositions prepared fromstyrene-ethylene-butylene-styrene tri-block and/orstyrene-ethylene-butylene di-block copolymers that are tackified (U.S.Pat. No. 4,822,653), a hot melt packaging adhesive comprising a ethylenen-butyl acrylate copolymer with n-butyl acrylate (U.S. Pat. No.4,816,306), polysaccharide esters containing acetal and aldehyde groups(U.S. Pat. No. 4,801,699), polysaccharide aldehyde derivatives (U.S.Pat. No. 4,788,280), an alkaline adhesive comprising a latex polymer ora halohydrin quaternary ammonium monomer and starch (U.S. Pat. No.4,775,706), polymeric fatty acid polyamides (U.S. Pat. No. 4,419,494),hot melt adhesives comprising resins containing 2-methylstyrene, styreneand a phenol (U.S. Pat. No. 4,412,030). The present invention is notrestricted to the listed adhesive compounds and compositions, as wouldbe apparent to those of skill in the art.

[0221] Such adhesive additives may comprise about 1 to 50 weight percentof the composition, more preferably, about 25 weight percent.

[0222] B. Adhesive/Coating Thermoset Additives

[0223] It is also possible to add a thermoset resin to the susceptorcompositions of the present invention. Such thermosets are capable ofbeing cross-linked or cured through heat and/or catalysts and includethose described in U.S. Pat. No. 5,182,134, e.g. epoxies, polyurethanes,curable polyesters, hybrid thermosets, and curable acrylics. Othersinclude bismaleimides, silicons, phenolics, polyamids and polysulfidesamong others. Further examples include maleate resins formed by thereaction of various polyols with maleic anhydride. Orthophthalic resinsmay be used which are formed by the reaction of phthalic anhydride andmaleic anhydride or fumaric anhydride as the dibasic acid. Isophthalicresins may also be used which may be formed by reacting isophthalic acidand maleic anhydride. Others include the bis-phenol fumarides,chlorendic polyester resins, vinyl esters, dicyclopentadiene resins,orthotolyl biguanine, the diglycidyl ether formed from bis-phenol A andepichlorohydrin, triglycidyl isocyanurate thermosetting compositions,bis-phenol A-epichlorohydrin diglycidyl ether cured with phenoliccross-linking agents, aliphatic urethane thermosetting compositions suchas an unblocked isofuron diisocyanate-E-caprolactam, BTDA thermosettingcompositions which are generally the reaction product of3,3,4,4-benzophenone tetracarboxylic dianhydride and a bis-phenolA-epichlorohydrin diglycidyl ether, hybrid thermosetting compositionswhich are the reaction product of a carboxylated saturated polyestercuring agents and bis-phenol A-epichlorohydrin diglycidyl ether,standard bis-phenol A-epichlorohydrin diglycidyl thermosets such asthose which are cured from 2-methylimidazole, and standard bis-phenolA-epichlorohydrin diglycidyl ether thermosets which are cured with2-methylimidazole and dicyandiamide thermosetting compositions. See U.S.Pat. Nos. 5,182,134, 5,387,623.

[0224] Other thermosets and adhesives/coatings that may be added to thesusceptor compositions of the invention include a reactive polyurethaneprepolymer and 2,2′-dimorpholinoethyl ether ordi(2,6-dimethylmorpholinylethyl) ether catalyst (see U.S. Pat. No.5,550,191), a free radical polymerizable acrylic monomer, diazoniumsalt/activator composition (see U.S. Pat. No. 4,602,073), adiphenylmethane diisocyanate, a caprolactone triol, a neopentyl adipateester diol, and, optionally, at least one polypropylene diol togetherwith a catalyst (U.S. Pat. No. 5,057,568), an aqueous polyurethanedispersion comprising an isocyanate-terminated polyurethane prepolymercontaining carboxylic acid salt groups, and an active hydrogencontaining chain extender (U.S. Pat. No. 4,801,644).

[0225] The susceptor compositions of the present invention may also becombined with a shelf stable thermosetting resin as described in U.S.Pat. No. 5,739,184, which is then activated by RF energy to givecoatings, e.g. for wood or paper products. This thermosetting resincomprises an epoxy resin, a rosin and an organometallic compound in anamount effective to provide improved adhesion to wood or papersubstrates.

[0226] Curing agents may also be combined together with thesusceptor/thermoset compositions of the invention, including melaminessuch as dialkyl melamines, amides such as dicyandiamide, adipamide,isophthalyl diamide, ureas such as ethylene thiourea or guanylurea,azides such as thiosemicarbazide, azoles such as guanazole or3-amino-1,2,4-triazole, and anilines such as dialkylanilines such asdimethyl aniline and diethyl aniline.

[0227] Such thermoset additives may comprise about 1 to 50 weightpercent of the composition, more preferably, about 25 weight percent.

[0228] It has also been discovered that thermoset compositions may beactivated with only the polar carrier and without a susceptor. Thus, theinvention also relates to compositions comprising a thermoset and apolar carrier. The thermoset may comprise about 60 to 95 weight percentof such a composition. The polar carrier may comprise about 5 to 40weight percent. The invention relates as well to methods of bonding,adhering or coating substrates with such thermoset/polar carriercompositions.

[0229] C. Surfactant Additives

[0230] According to another embodiment of the present invention,surfactant additives can be added to the susceptor composition toenhance the ability to draw down the susceptor composition of thepresent invention onto the layers or substrates to be bonded, adhered orcoated. Depending on the types of materials that are to be joined orcoated, surfactant additives, such as SURFYNOL 104PA (available from AirProducts Corporation) and SURFADONE LP 300 (N-dodecyl-2-pyrrolidone,available from International Specialty Products), can be used to wet avariety of substrates such as Mylar and polyethylene (PE). A furtherplasticizer is p-toluenesulfonamide, a good plasticizer that alsodissolves stannous chloride. The present invention is not restricted tothe listed surfactant additives, as would be apparent to those of skillin the art. Such surfactants may comprise about 0.1 to 5 weight percentof the composition.

[0231] D. Plasticizer Additives

[0232] The susceptor compositions of the present invention may furthercomprise a plasticizer to modify the flexibility of the adhesive orcoating. Examples of such plasticizers include, but are not limited toacetyl tributyl citrate, butyl benzyl phthalate, butyl phthalyl butylglycolate, dibutyl phthalate, dibutyl sebacate, diethyl phthalate,diethylene glycol dibenzoate, dipropylene glycol, dipropylene glycoldibenzoate, ethyl phthalyl ethyl glycolate, ethyl-p-toluene sulfonamide,hexylene glycol, methyl phthalyl ethyl glycolate, polyoxyethylene arylester, tributoxyethyl phthalate, triethylene glycol polyester of benzoicacid and phthalic acid, glycerin, or mixtures thereof. Otherplasticizers that may be used include N-methyl-2-pyrrolidone (NMP), andsubstituted toluene sulfonamides (e.g. p-toluenesulfonamide, RIT-CIZER#8™ and RIT-O-LITE MHPT from Rit-Chem Co., Inc., Pleasantville, N.Y.).Such plasticizers may comprise about 1 to 40 weight percent of thecomposition.

[0233] E. Tackifers

[0234] The tackiness of the compositions of the invention may beincreased by the addition of a suitable tackifier, e.g. one or more ofhydrogenated aromatic petroleum resins, hydrogenated aliphatic petroleumresins, and hydrogenated terpene resins (see U.S. Pat. No. 5,418,052),coumarone-indene, ester gum, gum rosin, hydrogenated rosin, phenolicmodified hydrocarbon resins, rosin esters, tall oil rosins, terpenephenolic, terpene resins, toluene sulfonamide-formaldehyde resin, woodrosin (see U.S. Pat. No. 5,442,001), distilled rosin, dimerized rosin,maleated rosin, polymerized rosin (see U.S. Pat. No. 5,532,306). Othertackifiers and modifiers, include (but are not limited to) styrene andalpha methyl styrene resins, glycerol and pentaerithritol esters, etc.Particular tackifiers include WINGTACK 95 from Goodyear, Herculin D andPICCOLYTE C from Hercules, EASTOTACK H100 from Eastman, and ECR 149B orECR 179A from Exxon Chemical (see U.S. Pat. No. 5,559,165). Othertackifiers include rosin and its derivatives available from ReicholdChemicals, Manila Copal (softening point 81-90° C. acid No.110-141),Pontianac (softening point 99-135° C. acid No. 1120129) and Sanarec(softening point 100-130° C., acid no. 117-155). Such tackifiers maycomprise about 1 to 25 weight percent of the composition.

[0235] F. Fillers

[0236] A number of different fillers may be added to the susceptorcompositions of the invention, including, but not limited to cellulose,bentonite, calcium carbonate, calcium silicate, clay, mica silica, talc,alumina, glass beads, fibers and the like. Such fillers may compriseabout 0 to 40 weight percent of the composition.

[0237] G. Stabilizers and Antioxidants

[0238] Stabilizers and antioxidants may be added to the susceptorcompositions of the invention in amounts effective to achieve theintended result. Included amoung such stabilizers include high molecularweight hindered phenols and multifunctional phenols such as sulfur andphosphorous-containing phenols. Representative hindered phenols include1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene,pentaerythritol tetrakis-3-(3,5-di-tert-butyl-4-hydroxypropionate,n-octadecyl-3,5-di-tert-butyl-4-hydroxyphenyl)propionate,4,4′-methylenebis(2,6-di-tert-butylphenol), 4,4′-thiobis(6-tert-butyl-o-cresol), 2,6-di-tert-butylphenol,6-(4-hydroxyphenoxy)-2,4-bis(n-octylthio)-1,3,5-triazine,di-n-octadecyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate,2-(n-octylthio)ethyl -3,5-di-tert-butyl-4-hydroxybenzoate, and sorbitolhexa[3-(3,5-di-tert-butyl-4-hydroxylphenyl)propionate (see U.S. Pat. No.5,574,076). Such stabilizers and antioxidants may comprise about 0.01 to5 weight percent of the composition.

[0239] H. Other Additives

[0240] According to another embodiment of the present invention, othertypes of additives to the susceptor composition may include flow aids,heat and UV stabilizers, coupling agents, waxes, pigments and otherorganic compounds. For example, in some instances, waxes can facilitatelower melt temperatures. Waxes that can be utilized include, but are notlimited to, Bees wax (SYNCHROWAX BB4), Candelilla wax, CARBOWAX 3350(available from Union Carbide Corporation), Carnauba wax, and CASTORWAXNF. Other waxes include N-(2-hydroxyethyl)-2,2′-ethylene-bis-stearamide,stearamide, 12-hydroxystearamide wax, hydrogenated castor oil, oxidizedsynthetic waxes, poly(ethylene oxide) having a molar average molecularweight of above about 1000, and functionalized synthetic waxes such ascarbonyl containing ESCOMER H101 from Exxon (see U.S. Pat. No.5,532,306). Preferably, the wax polar as described in U.S. Pat. No.5,750,605. A preferred polar wax is Peracin 200. Also preferably, thepolar wax is present at no more than about 25%, more preferably, no morethan 17% of the composition, most preferably, no more than 10% of thecomposition.

[0241] Other additives include elastomers such as those described inU.S. Pat. No. 5,506,298, 5,739,184, 5,169,890, 5,039,744, 4,761,198 maybe used, including styrene butadiene rubber, polybutadiene rubber,rubber, nitrile rubbers, butyl rubber and halogenated butyl rubber.

[0242] When the compositions are applied and activated as coatings, theymay further comprise one or more additives to impart color to thecomposition. Such additive include, without limitation, titaniumdioxide, iron oxide pigments, carbon black and organic pigments such asisoindoline yellow.

[0243] The present invention is not restricted to the listed additives,as would be apparent to those of skill in the art. Such other additivesmay comprise about 1 to 25 weight percent of the composition.

[0244] V. Applying the Susceptor Compositions to Substrates

[0245] The compositions of the invention may be formulated to be appliedas a liquid at room temperature, hot melt, or powder. Liquidcompositions may be solvent borne or water-borne. The liquid appliedcompositions may be applied as a liquid at room temperature and drieddown to give the desired coating. The liquid applied coating may beapplied to a substrate by any conventional method including spraying,ink-jet, brushing, rolling, gravure printing, dripping and the like.Methods of actively drying down liquid compositions include but are notlimited to conventional oven drying, forced air, heat lamps, microwaveheating, RF heating or various combinations of these or other methods.When a liquid composition is dried down, it loses some or all of itsvolatiles. RF drying of a liquid applied composition may be accomplishedby applying RF energy across the composition in order to generatesufficient heat within the liquid to facilitate or enhance theevaporative loss of water or solvent(s). The RF energy can be appliedacross the liquid at constant, intermittent, or gradient intensities toachieve the desired rate and degree of drying. Similarly, other methodsof drying may be applied at constant, intermittent or gradientintensities to achieve the desired drying result.

[0246] Hot melt applied systems are applied in their molten state at anelevated temperature and then cooled to yield the desired solid coating.The hot melt compositions can be heated to a molten state by variousmethods including but not limited to conventional melt tanks, microwaveheating and RF heating. Once the hot melt composition is melted, it maybe applied in a variety of different types of hot melt coatings,including but not limited to spirals and beads, hot blown, slot coat,and co-extrusion. After application, the molten hot melt composition canbe passively or actively cooled to return to its solid form. Activecooling may be accomplished by blowing cool air across the appliedmaterial, or by allowing the substrate to make contact with a heat-sinksurface.

[0247] Powdered applied systems are applied in their “fine” particlestate (1-20 μm) by electrostatic spray or gun. The applied layer isactivated by RF energy as in liquid or hot-melt systems.

[0248] Once dried and/or cooled, the substrate may be stored untilactivation of the composition is desired. Many of the appliedcompositions of the invention are substantially non-tacky and may beapplied to a substrate which is then rolled up. Upon unrolling andactivating, the substrate may be adhered to one or more othersubstrates. Those compositions that are tacky may be activatedimmediately after being applied and dried if necessary. Alternatively,they may be covered with a removable strip or dusted with talc orsimilar material.

[0249] One aspect of the invention also relates to a method for applyinga susceptor composition to a substrate, comprising:

[0250] (1) formulating the susceptor composition as a liquid dispersion;

[0251] (2) applying the liquid dispersion of the susceptor compositionto the substrate;

[0252] (3) drying the susceptor composition, wherein the drying stepincludes the step of applying RF energy across the composition, therebygenerating heat within the liquid dispersion. In a preferred embodiment,one may roll up the substrate after the susceptor composition has dried.

[0253] The susceptor compositions may be applied to any conventionalsubstrates including, without limitation, woven and nonwoven substratessuch as polyolefins, such as PP and PE webs, non-wovens, films and thelike, cellulose substrates prepared from, for example, wood pulp (suchas paper, cardboard and the like), cotton fibers (e.g. textiles such ascloth, sheeting and industrial fabrics), glass, ceramic surfaces, rubberand synthetic polymeric substrates such as polyester or polyolefinsubstrates prepared from, for example, polypropylene and polyethylene,polyvinyl alcohol, polyhydroxyvalerate butyrate, polylactides,cellulosics, polyamides, polyvinyl chloride, polystyrene, acrylics,synthetic textile products, etc. and any combination of theaforementioned. Other substrates include metal (e.g. aluminum foil andother metal foils), wood, composites, etc.

[0254] VI. Apparatus For Activating the Various Compositions of thePresent Invention

[0255] Generally, the compositions of the present invention may beheated (i.e., activated) by any system capable of generating anelectromagnetic field of sufficient strength and frequency.

[0256]FIG. 4 illustrates a high level block diagram of an RE heatingsystem 400 that is capable of generating an electromagnetic field foractivating the NO compositions of the present invention. Heating system400 includes an RF power supply 402 that provides about a 1 kW, 1 to 15MHz, RF signal 404 to a heat station 406.Heating system 400 alsoincludes an inductor 408 that is coupled to RF power supply 402 throughheat station 406. Generally, heat station 406 includes a capacitorconnected either in series with or parallel to inductor 408.

[0257] RF signal 404 provided to heat station 406 by RF power supply 402creates an alternating current flowing through inductor 408, whichcreates an electromagnetic field. Heating of a sample 410, which is orincludes a composition of the present invention, occurs when sample 410is placed in proximity to inductor 408. The best heating takes placewhen sample 410 is placed near the proximal (or “terminal”) end 411 ofinductor 408, and little or no heating occurs when sample 410 is placedat the distal (or “turn”) end 412 of inductor 408. Further, there is aheating gradient from terminal end 411 to turn end 412. In theory andwithout limitation, the best heating occurs at the terminal end 411because it is believed that the intensity of the electric fieldcomponent of the electromagnetic field at terminal end 411 is greaterthan at the distal end 412.

[0258]FIG. 5 illustrates a high level block diagram of anotherembodiment of a heating system 500 that is capable of generating anelectromagnetic field for activating the compositions of the presentinvention. Heating system 500 includes an alternating voltage generator502 and a probe 504, which is connected to an output terminal 501 ofvoltage generator 502. Voltage generator 502 alternately positivelycharges and negatively charges probe 504, thereby creating anelectromagnetic field 506 centered at probe 504.Heating can occur whensample 410 is placed in proximity to probe 504.How quickly and how muchheating occurs depends on the sample itself, the strength of theelectromagnetic field at the sample, and the frequency of thealternating voltage 509 produced by voltage generator 502.

[0259] Generally, probe 504 is a conductive material, such as, but notlimited to copper, aluminum, or stainless steel. Generally, probe 504can have a variety of shapes, including cylindrical, square,rectangular, triangular, etc. Preferably, probe 504 is square orrectangular. Probe 504 can be hollow or solid, preferably hollow.Generally, probe 504 can be straight or non-straight, such as curved.The preferred characteristics of probe 504 ultimately depends on theapplication that it is being used for.

[0260] In yet another embodiment, which is illustrated in FIG. 6,heating system 500 includes at least two probes 602 and 604 foractivating the compositions of the present invention. Probe 602 isconnected to output terminal 610, and probe 604 is connected to outputterminal 612. Like probe 504, probes 602 and 604 are made fromconductive materials as discussed above. Probes 602 and 604 can have avariety of shapes. For example, they can be either straight or curved.Preferably, at least a portion of probe 602 is parallel to a portion ofprobe 604, although not a required.

[0261] In the system shown in FIG. 6, probe 602 has a net positivecharge when probe 604 has a net negative charge, and probe 602 has a netnegative charge when probe 604 has a net positive charge. When probes602 and 604 are oppositely charged, a strong electromagnetic field 606is present between the probes. Thus, sample 410 is preferably heated byplacing it in a region above (or equivalently below) the region betweenprobe 602 and probe 604, as illustrated in FIGS. 7A and 7B. This regionis referred to as an activation region. Preferably, an insulating layer702 (see FIG. 7A) is placed between sample 410 and probes 602 and 604,although this is not a requirement.

[0262] Generally, the vertical distance between sample 410 and probes602 and 604 ranges from about 0.01 to 2 inches, more preferably fromabout 0.02 to 1 inch, and most preferably from about 0.025 to 0.185inches. Sample 410 can also be heated by placing it between probes 602and 604. Generally, The center to center distance between probes 602 and604 ranges from about 0.1 to 3 inches, more preferably from about 0.2 to2 inches, and most preferably from about 0.25 to 0.75 inches.Additionally, in general, the height and width of a rectangular probe,or the diameter for a cylindrical probe, ranges between about 0.02 and0.5 inches, and the length generally ranges from about 0.25 inches to 20feet.

[0263] In one embodiment, the distal end 750 of probe 602 is curled toreduce corona effect (see FIG. 7C). For the same reason, the distal endof probe 604 is also curled.

[0264] An advantage that the two probe system shown in FIG. 6 has overthe system shown in FIG. 4, is that sample 410 heats equally as well atthe proximal end of probes 602, 604 as it does at the distal end.Consequently, the system of FIG. 6 does not experience the heatinggradient problem that is encountered with the system of FIG. 4.

[0265] Generally, the compositions of the present invention may beactivated by a frequency of the alternating voltage 509 ranging fromabout 1 KHz to 5 GHz, more preferably from about 1 MHz to 80 MHz, andmost preferably from about 10 to 15 MHz. The peak to peak voltagebetween probes 602 and 604 generally ranges from 1 to 15 kilo volts(kV). Generally, the duration of RF energy application to the sample 410(also referred to as dwell time), for most applications, ranges fromabout 100 milliseconds to 30 seconds. However, there are someapplications where the dwell time greatly exceeds 30 seconds. In thecase of a composition comprising a thermoset resin, the dwell timeranges from about 1 second to 20 minutes, preferably from about 1 to 10minutes, and most preferably from about 2.5 to 5.0 minutes to initiatecross linking reactions(s) leading to a high degree of thermosetcharacter.

[0266]FIG. 8 illustrates one embodiment of alternating voltage supply502. The invention, however, is not limited to this or any particularvoltage supply, since any system capable of generating a strong enoughelectromagnetic field could be utilized to activate the compositions ofthe present invention. In one embodiment, voltage supply 502 includesdirect current (DC) voltage source 802 that is connected to a broadbandamplifier 806 through DC power rail 804. The function of DC voltagesource 802 is to provide a DC voltage to broadband amplifier 806. The DCvoltage produced by DC voltage source 802 can range from 0 volts to 200volts. The magnitude of the voltage provided to broadband amplifier 806is dependent upon an output signal 815 from a main controller 814.Output signal 815 of main controller 814 can be controlled manually by auser 821 through user interface 820, or automatically by a productionline control system 822.

[0267] Broadband amplifier 806 amplifies a low level RF signal 817generated by frequency controller 816, and thus generates a high levelRF power signal 808. Preferably, the frequency of RF signal 817 rangesbetween 10 MHz and 15MHz. RF signal 808 is passed through a power sensor810 and provided to an impedance matching circuit 812 (also referred toherein as “heat station”) through an RG393 50 ohm cable 811. Upon RFsignal 808 being inputted into impedance matching circuit 812, anelectromagnetic field 606 is generated at the probes 602 and 604; Thiselectromagnetic field is used to heat the compositions of the presentinvention.

[0268] While RF signal 808 is applied to impedance matching circuit 812,power sensor 810 continuously feeds a reflected power signal 832 tofrequency controller 816 and main controller 814. Power sensor 810 alsocontinuously feeds a forward power signal to main controller 814.Reflected power signal 832 represents the amount of reflected power andforward power signal 830 represents the amount of forward power.

[0269] Frequency controller 816 uses reflected power signal 832 tocontinually adjust the frequency of RF signal 817 so as to minimize theamount of reflected power. Main controller 814 uses forward power signal830 and reflected power signal 832 to maintain the power level set byuser 821 through user interface 820 or set by production line controlsystem 822. Main controller maintains the correct power level byadjusting the level of DC voltage supplied by DC voltage source 802 andby adjusting the output level of RF signal 817 generated by frequencycontroller 816.

[0270] As sample 410 changes during a heating process, the impedance onthe probes 602 and 604 change, which causes a change in the forward andreflected power. Frequency controller 816 will detect this change inreflected power because it is receiving reflected power signal 832 frompower sensor 810. Frequency controller 816 changes the frequency of RFsignal 817 so as to minimize reflected power, thereby achieving anoptimum impedance match and insuring a repetitive power transfer fromheating system 800 to sample 410.

[0271] DC voltage source 802, sensor 810, frequency controller 416, andmain controller 814 are further described in U.S. patent applicationSer. No. 09/113,518, entitled, “RF Power Supply,” which is incorporatedherein by reference in its entirety. A broadband amplifier suitable foruse in heating system 800 is described in U.S. patent application Ser.No. 09/270,506, filed Mar. 17,1999, entitled, “High Frequency PowerAmplifier,” which is incorporated in its entirety herein by reference.

[0272]FIG. 9 is a flow chart illustrating a process for heating acomposition according to the present invention using heating system 800.The process begins with step 902 when user 821 or production linecontrol system 822 sends a “heat-on” signal to the main controller 814.Upon receiving the “heat-on” signal, main controller 814 begins aninitial tunning process for determining the frequency of RF signal 817that produces the minimum amount of reflected power. The initial tuningprocess encompasses steps 904-908. In step 904, main controller 814directs DC voltage source 802 to output a “tune” voltage. The “tune”voltage is the lowest voltage level that can provide a sufficient signalto measure the reflected power over a range of frequencies. Theobjective is to consume the least amount of energy during the initialtunning process. Typically, the “tune” voltage level is 10% of the fullscale voltage, where the full scale voltage is the voltage at which thecomposition is intended to be heated.

[0273] After step 904, control passes to step 906. In step 906, heatingsystem 800 performs course tunning. That is, heating system 800determines a course estimate (i.e., rough estimate) of the frequencythat produces the minimum reflected power. Hereafter this frequencyshall be referred to as the resonant frequency. The course estimate ofthe resonant frequency can be determined by sampling reflected powerover a first predetermined frequency range. After step 906, controlpasses to step 908. In step 908, the heating system 800 performs finetunning. That is, the heating system 800 determines a fine estimate(i.e., more precise estimate) of the resonant frequency. The fineestimate can be determined by sampling the reflected power over a secondfrequency range, which includes the course estimate of the resonantfrequency. After step 908, control passes to steps 910 and 912 inparallel. In step 910, main controller 814 ramps (i.e., rapidlyincreases) the voltage output by the DC voltage source 802 such thatwithin approximately 30 milliseconds the voltage increases from the“tuning” voltage level to approximately the full scale voltage level. Instep 912, the heating system 800 continuously tracks the resonantfrequency until a power off indication is received. The methods forcourse tuning, fine tuning, and tracking resonant frequency aredescribed in U.S. patent application Ser. No. 09/113,518.

[0274]FIG. 10A further illustrates one embodiment of impedance matchingcircuit 812. Impedance-matching circuit 812 is used to match theimpedance of 50 ohms on the input to the variable impedance of theprobes 602 and 604 and sample 410. The impedance of the probes 602 and604 and sample 410 is typically in the order of 200 to 500 ohms. Theimpedance of the sample has an equivalent circuit of a resistancebetween 500 Ohms and 50 Kilo Ohms in parallel with a 0.1 picofaradcapacitor.

[0275] Circuit 812 includes a connector 1001, two capacitors 1002 and1004, and an inductor 1006. Capacitor 1002 is a variable capacitor,which is adjustable from 10 to 50 picofarades (pf) to achieve impedancematch to the varying impedance of probes 602 and 604 and sample 410. Thecapacitance of capacitor 1004 is preferably 100 pf, and the inductanceof inductor 1006 is preferably 1.0 micro henries (μH). Capacitor 1004and inductor 1006 form a parallel resonance circuit that will resonatetypically at a frequency between 12.5 and 14.5 MHz. Capacitor 1004 andinductor 1006 are water cooled with a flow rate of approximately half agallon per minute. Probe 602 is connected to a node 1020 of circuit 812,and probe 604 is connected to a node 1022 of circuit 812. The high powerRF input 411 (typically less than 1 kilowatt) from a 50 ohm sourcegenerator is connected to connector 1001.

[0276] A process for setting the capacitance of variable capacitor 1002will now be described. The process begins by applying a low level RFsignal (typically 10 watts) to input 1001 of circuit 812. The frequencyof the applied RF signal is adjusted until the amount of reflected poweris minimized. The capacitance of capacitor 1002 is then adjusted tooptimize the reflected power minima. To achieve the least amount ofreflected power that is practical to achieve, which is about two percentreflected power (or 1.25 voltage standing wave ratio (VSWR)). thefrequency of the applied RF signal and the capacitance of capacitor 1002are adjusted in an iterative process. Once the process is completed,sample 410 is placed in proximity to probes 602 and 604. At this pointit may be necessary to adjust the frequency of operation and capacitor1002 in order to achieve an optimum reflected power. Once optimumreflected power is achieved, the power level of the input RF signal isincreased. As the input RF power level is increased the resonantfrequency of the matching circuit and probes 602 and 604 and sample 410will change requiring a change of operating frequency to continue tominimize the reflected power.

[0277]FIG. 10B illustrates another embodiment of impedance matchingcircuit 812. In this embodiment, impedance matching circuit 812 includesa connector 1051, a 1:1 balun transformer 1052, two variable capacitors1054 and 1056, and one inductor 1060. Capacitors 1054 and 1056 areadjustable from about 3 to 25 picofarades (pf) to achieve impedancematch to the varying impedance of probes 1082 and 1084 and sample 410.The inductance of inductor 1060 is preferably about 5 micro henries(mH). Capacitor 1058 is not an actual circuit element of the impedancematching circuit 812. Capacitor 1058 represents the capacitanceassociated with the inductor system, which consists of the inductor1060, the leads (not shown) connecting the inductor 1060 to thecapacitors 1054 and 1056, and the leads (not shown) connecting theprobes 1082 and 1084 to the inductor 1060. The capacitance of capacitor1058 is preferably less than about 15 pf. One advantage the impedancematching circuit 812 shown in FIG. 10B has over the impedance matchingcircuit shown in FIG. 10A, is that the impedance matching circuit 812shown in FIG. 10B provides a balanced signal on the probes 1082 and 1084relative to ground.

[0278] VII. Method of Bonding Substrates

[0279] The compositions of the present invention may be employed in avariety of bonding methods, including but not limited to adhesivebonding, thermal bonding and mechanical bonding.

[0280] Adhesive bonding is accomplished when a susceptor composition isinterposed between two substrates that are to be joined (adherands) andactivated by RF energy to undergo adhesive attachment to each of theadherands.

[0281] In the case of thermoplastic adhesive compositions such as hotmelts, RF energy causes the composition to melt and wet-out ontoadherands that are in close contact. Upon cooling, the compositionreturns to a solid state with sufficient cohesive strength and adhesionto each of the adherands to form a good bond. The degree of heating andmelting of the adhesive composition is controlled by the intensity andduration of the applied RF energy and the formulation of the adhesivecomposition. Such control is required to prevent undesired resultsstemming from under-heating or over-heating the adhesive composition.For example, under-heating can result in a weak bond due to insufficientwet-out of the adhesive onto the adherands. Also, over-heating canresult in undesirable bond, with thermal distortion or destruction ofthe adherands, as well as thermal degradation of the thermoplasticcomposition.

[0282] In the case of thermoset adhesive compositions, RF energy causesthe composition to become cured, resulting in sufficient increase incohesive strength and adhesion to adherands to form a strong bond. As inthe case of thermoplastic compositions, the degree of heating and curingof thermoset compositions is controlled by the intensity and duration ofthe applied RF energy. Such control is required to prevent undesiredresults from under-heating or over-heating. For example, under-heatingcan result in a weak bond due to insufficient cross-linking.Over-heating can cause effects such as thermal distortion or destructionof the adherands, as well as thermal degradation and excessive shrinkageof the thermosetting composition.

[0283] Thermal bonding is accomplished when the composition is used togenerate sufficient heat to cause one or more adherands to becomethermally fused to each other.

[0284] One example of thermal bonding involves saturating a porousthermoplastic material, such as a non-woven polypropylene web, with anRF-heatable composition, and then interposing the saturated web ofmaterial between two adherands and RF-heating the composition to causethe saturated web and adjacent adherands to melt and fuse to each other.

[0285] Another example of thermal bonding involves saturating a porous,first thermoplastic adherand with an RF-heatable composition, and thenplacing the first adherand against a second thermoplastic adherand andRF-heating the composition to cause the first and second adherands tomelt and fuse together.

[0286]FIG. 11 shows a method of bonding polyolefin and non-polyolefinmaterials using a composition that is activated in the presence of RFenergy according to the present invention.

[0287] In step 1102, adherands that are to be bonded or adhered arechosen. Once the materials or layers are chosen, an appropriatecomposition is prepared in step 1104. For example, if nonwoven PP layersare chosen to be bonded, a susceptor, which includes an ionomer asdescribed herein, is combined with a polar carrier. The type ofcomposition may depend on whether a transparent, translucent, or lightlycolored adhesive obtained by the method of the present invention isneeded for a particular application. After the composition is preparedin step 1104, control can pass to step 1106, 1109, or 1110.

[0288] In step 1106, a second carrier, such as an insoluble porouscarrier (e.g., nonwoven PP), is saturated with the prepared composition.In step 1108, the saturated insoluble porous carrier is then placed inbetween the layers chosen to be bonded. RF energy is applied in step1120. The RF energy applied in step 1120 can be applied for 100milliseconds to several minutes; The application of RF energy allows forthe precision heating of the layers to be bonded, without the unwantedside effects of non-uniform bonding, or damage to the bonded layers.

[0289] In step 1110, one or both of the layers to be bonded are coatedwith the composition. In step 1112, the composition is allowed to dry orthe hot melt to congeal depending on the type of composition created.Alternatively, a heat source (e.g. an oven or lamp) and fan may be usedto dry the coating or RF energy may be applied to drive off any water orother solvents. According to step 1114, the layers to be bonded areplaced together, such that the coated surfaces are in contact. Uniformpressure placed on the contacted layers helps enhance the bonding oradhesion process activated by the applied RF energy (step 1120). Suchuniform pressure may be applied while the composition is being activatedor immediately thereafter by use of conventional nip rollers.

[0290] In step 1109, a film of the composition is created. Such a filmcan be created according to film making processes well known in the art.The film made in step 1109 can then be sandwiched between the twomaterials to be bonded in step 1111. RF power is then applied inaccordance with step 1120.

[0291] In a further embodiment, two or more adherands may be bonded oradhered by a process comprising: applying a first composition, onto afirst adherand; applying a second composition onto a second adherand;contacting the first composition with the second composition; applyingRF energy to the first and second compositions to heat the compositions,thereby causing the first and second adherands to become adhered orbonded; wherein one of the compositions comprises a susceptor and theother of the susceptors is a polar carrier, and the susceptor and/or thecarrier are present in amounts effective to allow the first and secondcompositions to be heated by RF energy.

[0292] In this embodiment of the invention, the susceptor and carriercomponents of the composition are applied separately to the adherandsprior to placing the adherands together. FIG. 52 shows asusceptor-coated adherand 5201 assembled to an adherand 5203 coated withthe polar carrier. After coating one or both of the adherands, one mayapply a temporary release liner 5205 to the coated side to allow thecoated adherand to be rolled up or stacked. Alternatively, one may dryone or both coatings.

[0293] After nipping the two coated adherands in the assembly stage, theassembly is passed through an RF field 5207 for activation. The RFenergy causes the susceptor and carrier to heat with the resultingadhesion between the two adherands. The final nip rollers 5209 press andbonds the two adherands, while cooling the bond line.

[0294]FIG. 53 shows the replacement of the pre-applied polar carrier onthe adherand with a polar carrier spray coated onto the adherand justprior to the assembly nip rollers 5206. A polar carrier is applied (e.g.sprayed or otherwise as described herein) by a spray applicator 5302onto adherand 5201. When assembled with the susceptor coated adherand5203 and exposed to RF energy, the interfaced composition activates toform a bond.

[0295] VIII. Additional Probe Embodiments

[0296] Additional embodiments of probes 602 and 604 are described belowwith reference to FIGS. 12 to 17. These additional embodiments are in noway limiting and merely provide additional examples of possibleconfigurations of the probes.

[0297] In FIG. 12, probes 602 and 604 are each curvilinear andoppositely charged. In this particular example, probes 602 and 604 aresinusoidally or “S” shaped, but any similar arrangement is possible.Probes 602 and 604 are made from conductive materials, as describedabove, preferably, but not limited to, copper, aluminum, or stainlesssteel. Probe 602 includes a proximal region 1206, and activation region1208 and a distal region 1210. Similarly, probe 604 includes a proximalregion 1212, an activation region 1214, and a distal region 1216. Inproximal regions 1206 and 1212, probes 602 and 604 are spaced apart inorder to prevent arcing. The amount of spacing depends on the size ofprobes 602 and 604, and in one example, probes of 0.125 inch squarecross-section should be spaced at least 1.1875 inches apart. Similarly,distal regions 1210 and 1216 are spaced apart-to prevent arcing, theamount of such spacing is similarly dependent upon the size of theprobes. In activation regions 1208 and 1214, probes 602 and 604 are inproximity to one another in order to create an electromagnetic fieldbetween the probes. How close probes 602 and 604 must be to one anotheragain depends on the size of the probes and the magnitude of the chargeon them. In one example, probes 602 and 604 have about a 0.125 inchsquare cross-section and preferably spaced between 0.25 and 0.75 inchesapart. It is preferable the space between probes 602 and 604 remainssubstantially equal throughout the activation region, but it is notnecessary. An activation zone 1222 is defined in activation regions 1208and 1214 between an outermost end 1218 of probe 602 and an outermost end1220 of probe 604. Activation zone 1222 is indicated in dashed lines inFIG. 12. Activation zone 1222 defines the area of sample 410 that can beheated/activated by the system when the substrates being joined aremoving in the direction indicated. If the substrates are stationary withrespect to the probes, the activation zone is defined by the area inbetween the probes.

[0298] In another embodiment, probes 602 and 604 may be repeated inorder to provide a larger activation zone. Such an arrangement is shownin FIGS. 13A, 13B and 13C. For example, in FIG. 13A, a pattern of oneprobe 602 and two probes 604 is provided. This arrangement may includeany number of probes 602 and 604, as long as oppositely charged probesare placed next to one another. This arrangement works equally well withmultiple sets of curvilinear probes, as shown in FIG. 13B.

[0299]FIG. 13C illustrates one embodiment of what is termed an“interdigitated probe system.” The interdigitated probe system 1301 isadvantageous because it provides an extended activation zone, as shownby the dotted rectangle 1350. Interdigitated probe system 1301 includesa first element 1302 and a second element 1304.

[0300] The first element 1302 includes a first conductor 1310 and one ormore second conductors 1322 connected to the first conductor 1310.Preferably, conductors 1322 are coplanar and uniformly spaced apart, butthis is not a requirement. Additionally, in one configuration of element1302, each conductor 1322 forms a right angle with conductor 1310, butthis is also not a requirement.

[0301] Similarly, the second element 1304 includes a first conductor1312 and one or more second conductors 1320 connected to the firstconductor 1312. Preferably, conductors 1320 are coplanar and uniformlyspaced apart, but this is not a requirement. Additionally, in oneconfiguration of element 1304, each conductor 1320 forms a-right anglewith conductor 1312, but this is also not a requirement.

[0302] In one embodiment, first element 1302 and second element 1304 areorientated such that conductors 1320 are coplanar with conductors 1322and each conductor 1320 is adjacent to at least one conductor 1322.First element 1302 and second element 1304 are not limited to anyparticular type of conductive material. However, conductors 1310, 1312,1320, and 1322 are preferably copper, and more particularly, coppertubes. In one embodiment, the copper tubes have a one-eighth of an inchdiameter.

[0303] In one embodiment, the length of conductors 1310 and 1312 isabout 40 inches, and the length of conductors 1320 and 1322 is about 2inches. However, conductors 1310, 1312, 1320, and 1322 are not limitedto any particular length. Typically, the length of conductors 1310 and1312 ranges between about 3 inches and 80 inches, and the length ofconductors 1320 and 1322 ranges between about 1 inch and 70 inches.

[0304]FIG. 14 shows another embodiment of a probe system for activatinga multi-sided sample 1402. In this embodiment, sample 1402 is mounted ona block 1404. Sample 1402 may be mounted on any similar device whichallows each side of sample 1402 to be exposed to moving probe blocks1406. This particular example shows a three-sided sample exposed tothree moving probe blocks 1406, however, the sample may include moresides and be exposed to an equivalent amount of moving probe blocks.Probe blocks 1406 include probes 602 and 604 mounted in an electricallyinsulating material such as, but not limited to, polytetrafluoroethylene(TEFLON™). Probes 602 and 604 are mounted on pressure plates 1408 ofprobe blocks 1406. In this particular example, three probes are used ineach probe block 1406, two negatively charged probes 604 and onepositively charged probe 602.However, more or less probes can be used,depending on the size of the probe blocks, as long as adjacent probesare oppositely charged. Probes 602 and 604 are coupled to an alternatingvoltage supply 502, via output terminals 610 and 612 as generally shownin FIG. 6. Probe blocks 1406 are moved into proximity of sample 1402mounted on block 1404, preferably between 0.125 and 0.375 inch, therebyactivating the compositions of the present invention, as previouslydescribed. Alternatively, probe blocks 1406 could be placed at theappropriate interval and block 1404 with sample 1402 could be moved intoposition to be activated. While FIG. 14 shows the probe blocks 1406 ashaving a regular shape, one skilled in the art will recognize that theprobe blocks could be any three dimensional shaped object.

[0305]FIG. 15 shows another embodiment for activating a multi-sidedsample 1502 using a stationary probe system. In this embodiment, probes602 and 604 are mounted on multiple sides of a single probe block 1504,similar to the manner in which probes 602 and 604 were mounted in probeblocks 1406. described above. In this particular example, probes 602 aremounted on three sides of a generally square probe block 1504, butprobes 602 and 604 could be mounted on multiple sides of any polygonalblock or three dimensional object. Sample 1502 is brought into proximityof probe block 1504 by pressure plates 1506, thereby activating thecompositions of the present invention, as previously described. In thisparticular example, two negatively charged probes 604 and one positivelycharged probe 602 are shown on each side of probe block 1504, however,it will be recognized that any number of probes could be utilized,depending on the application, as long as adjacent probes are oppositelycharged. Probes 602 and 604 are coupled to an alternating voltage source502 via output terminals 610 and 612, as generally depicted in FIG. 6.

[0306]FIGS. 16A and 16B show yet another embodiment of a probe systemfor activating a sample material including compositions of the presentinvention. In FIGS. 16A and 16B, sample 1602 is draped over a conveyorrod 1604 and generally moves along the circumference of the conveyorrod. Conveyor rod 1604 is constructed of electrically non-conductivematerial. A probe system 1606 is disposed in proximity to a portion ofthe circumference of conveyor rod 1604, e.g., 0.02 to 1.5 inches, andmore preferably within 0.125 to 0.375 inch, and is shaped to conform tothe shape of conveyor rod 1604, as best seen in FIG. 16B. Probe system1606 includes adjacent alternately charged probes 602 and 604 foractivating sample 1602. Probes 602 and 604 are coupled to an alternatingvoltage source 502, as generally depicted in FIG. 6.

[0307] The probe systems described above all activate a single side ofthe sample material. However, probe systems could be placed on bothsides of the material in each of the above-described embodiments,provided that the polarity of the probes is such that theelectromagnetic fields do not cancel each other out. A particularexample of an activation system for activating both sides of thematerial is shown in FIG. 17. Rather than using a probe system, twooppositely charged conductive plates 1702 (positively charge) and 1704(negatively charged) are disposed on opposite sides of sample material1706. Plates 1702 and 1704 are preferably constructed of copper, but maybe constructed of any suitable conductive material, such as theaforementioned conductive materials of probes 602 and 604. Samplematerial 1706 may be stationary or moving when exposed to the activationregion between plates 1702 and 1704. Plates 1702 and 1704 are preferablyspaced between 0.02 and 24 inches, more preferably between 0.02 and 15inches, and most preferably between 0.05 and 0.375 inches. Plates 1702and 1704 are coupled to an alternating voltage source 502 via outputterminals 610 and 612, as generally depicted in FIG. 6.

[0308] IX. Applicator System for Applying a Composition of the PresentInvention to a Substrate/Adherand

[0309]FIG. 18 illustrates one embodiment of an application system 1800for applying a composition according to the present invention to anadherand 1810. The manufacturing system includes an applicator 1815.Applicator 1815 applies a hot melt or liquid dispersion or powder of thecomposition 1812 to one side of adherand 1810. Composition 1812 may beapplied via a hot melt by applying heat to the composition 1812 so thatit reaches its melting point and can be applied to an adherand. In a hotmelt application heat is applied to the composition 1812 in theapplicator 1815, arid the composition 1812 is applied to the adherand ata temperature between 200 and 325 degrees Fahrenheit, preferably 250degrees Fahrenheit.

[0310] Composition 1812 may also be formulated as a liquid dispersion.The composition 1812 can then be applied to the adherand at roomtemperature. Once the liquid dispersion composition 1812 is applied tothe adherand, the coated material 1810 is passed through a heatingsystem 1820.Heating system 1820 acts to dry the composition 1812.Heatingsystem 1820 can be any conventional heating system, like an oven, orheating system 1820 can be an RF heating system, such as heating system500 described above. Other drying means that may be employed include,for example, a heat lamp with or without a fan to remove volatiles, ormicrowave heating system.

[0311] Composition 1812 can be applied in powder form by conventionalelectrostatic gun/spray.

[0312] In one embodiment, the coated adherand 1810 is rolled onto aroller 1830 after composition 1812 is sufficiently dried. Alternatively,the coated adherand 1810 can be cut into pieces and stacked. The coatedsusceptor 1810 can be used at a later point in time in the bondingprocess described above. The bonding process can occur anytime within afew seconds up to many months after the adherand 1810 has been coatedwith composition 1812.

[0313] X. Systems for Adhering or Bonding Two Adherands.

[0314]FIG. 19 illustrates one embodiment of a system for bonding oradhering various adherands or layers. The system utilizes RF heatingsystem 400, including power supply 402, cable 404, heat station 406, andcoil 408, and clamp 1902. The adherands to be bonded by RF heating 400,shown as layers 1910, pass through or in proximity to coil 408. Layers1910 can either be coated with a suitable susceptor composition, cansandwich a film made from a susceptor composition or can sandwich aninsoluble, porous carrier (such as a thermoplastic carrier web) that issaturated with a susceptor composition as described above. A clamp 1902provides uniform pressure to the adherands to be bonded or adhered.Alternatively, coil 408 can be implemented to provide a uniform pressureto the adherands to be bonded or adhered; Precision bonding or adheringtakes place as the layers 1910 are exposed to the electromagnetic fieldgenerated when an alternating current flows through coil 408. Theelectromagnetic field has sufficient RF energy to activate the bondingcomposition. Preferably, layers 1910 are exposed to the electromagneticfield for at least 100 milliseconds to several seconds or minutes. Inthe case of thermoset compositions, in general, longer times are needed,e.g. from 1 second to several minutes or hours.

[0315]FIGS. 20A and 20B illustrates a static bonding system 2000 forbonding or adhering adherands 2090 and 2092 (see FIG. 20B). Bondingsystem 2000 is referred to as a static because the adherands to bebonded do not substantially move while they are being exposed to theelectromagnetic field that activates an RF activatable composition whichis located between the adherands.

[0316] Referring now to FIG. 20A, bonding system 2000 includes a powersupply, such as voltage supply 502, for generating an alternatingvoltage between output terminal 612 and output terminal 610. Connectedto output terminal 612 is a probe 2006, and connected to output terminal610 is a probe 2008. The characteristics of probe 2006 and probe 2008are described above with reference to probes 602 and 604. In oneembodiment, probe 2006 and 2008 are rectangular hollow tubes made from aconductive material, preferably copper. Preferably, the height (H) andwidth (W) of each probe is about equal, and the length (L) is generallylarger than the height and width. For example, in one embodiment, theheight and width of each probe is about {fraction (1/8)} of an inch,whereas the length of each probe is about 10 inches. In general, theheight and width of a rectangular probe, or the diameter for acylindrical probe, ranges between about 0.02 and 0.5 inches, and thelength generally ranges from about 0.25 inches to 20 feet.

[0317] System 2000 is not limited to two probes. A third probe (notshown) could be placed adjacent to probe 2006 such that probe 2006 willthen be between the new probe and probe 2008. With this configuration,the new probe would be connected to the output terminal that probe 2008is connected to, which in this case is terminal 610. An exemplary threeprobed system is illustrated in FIG. 13A. One skilled in the art shouldrecognize that any number of probes could be used, provided that no twoadjacent probes are connected to the same output terminal of voltagesupply 502.

[0318] In one embodiment, probes 2006 and 2008. are placed in anelectrically insulating block 2010. Insulating block 2010 is composed ofan electrically insulating material, such as, but not limited topolytetrafluoroethylene (TEFLON™). An optional electrically insulatinglayer 2012 (see FIG. 20B) may be placed on top of probes 2006 and 2008.Preferably, electrically insulating layer is made frompolytetrafluoroethylene or other like material which resists adhesion ofthe substrates or adherands thereto.

[0319] An alternative electrically insulating block 2050 is illustratedin FIG. 20C. FIG. 20C shows a cross-sectional view of probes 2006 and2008 housed within the insulating block 2050. Insulating block 2050 isformed from two elements, insulating element 2052 and insulating element2054.

[0320] Insulating element 2052 has two U shaped recesses 2056 and 2058for receiving probes 2006 and 2008, respectively. In one embodiment, alow dielectric encapsulate 2060 is placed with the probes in therecesses. Insulating element 2054 has two protrusions 2062 and 2064 formating with the recesses 2056 and 2058 of insulating element 2052.Preferably, both insulating element 2052 and insulating element 2054consist primarily of polytetrafluoroethylene (TEFLON™).

[0321] Referring now to FIG. 20B, to bond adherand 2090 to adherand2092, adherand 2090 and/or adherand 2092 is coated with a suitablecomposition 2091, or a film of the composition 2091 is sandwichedbetween adherand 2090 and adherand 2092, or an insoluble porous carrieris saturated with composition 2091 and placed between adherand 2090 andadherand 2092. Adherands 2090 and 2092 are then placed over probes 2006and 2008 such that composition 2091 is between the adherands and overthe region between probe 2006 and probe 2008, as shown. Power supply 502is then activated, which creates an alternating voltage betweenterminals 612 and 610, which creates an electromagnetic field betweenprobes 2006 and 2008. The composition 2091 is exposed to theelectromagnetic field for a predetermined amount of time. Thepredetermined amount of time can range between about 100 milliseconds toabout one second, several minutes, or hours depending on the compositionand/or the strength of the electromagnetic field. The electromagneticfield causes composition 2091 to heat. When composition 2091 reaches agiven temperature, the composition will begin to melt and flow, causingan impedance change on the matching circuit 812. The impedance changecan be detected by a change in reflected power signal 832. This changein reflected power signal 832 can be used to control the intensity ofthe RF energy. Other methods of detecting when composition 2091 melts isto detect displacement of a pressure plate 2020 with a feed back loop.After the predetermined amount of time has expired or while thecomposition is exposed to the electromagnetic field, the adherand can bepressed together using pressure plate 2020, pressure roller (not shown),or any other pressure delivery apparatus or means, thereby assuring agood bond.

[0322] The resulting bond can be an adhesive bond, mechanical bond,thermal bond, or any combination of aforementioned bonds. For example,composition 2091 may have adhesive properties to create an adhesive bondbetween adherands 2090 and 2092, and/or composition 2091 may be used asa source of thermal energy for welding the adherands together.

[0323] An advantage of the present invention is that non-electricallyconductive materials can be stacked on top of an adherand withoutaffecting the bonding process. Only composition 2091 is directly heatedwhen the layers are exposed to RF energy having the preferred frequencyrange of 10 to 15 MHz. Thus, by selectively heating only the composition2091, multiple layers may be assembled prior to forming the bond betweenadherands 2090 and 2092. This allows the assembly of complex laminatesprior to bonding.

[0324] Another advantage of the present invention is that RF energy canbe re-applied to the bonded product and the two (or more) adherands 2090and 2092 can be disassembled. This is known as de-activating thecomposition 2091. In fact, the composition 2091 can be activated andde-activated a number of times.

[0325]FIGS. 38 and 39 illustrate two exemplary manufacturing systems inwhich static bonding system 2000 could be utilized. FIG. 38 illustratesa step and repeat manufacturing system. There are many applications ingeneral manufacturing where adherands are joined or bonded togetherusing an adhesive. In a conventional step and repeat joining (orbonding) system there is a gluing station immediately followed by ajoining station. The gluing station applies an adhesive to an adherand.After the adhesive is applied, the adherand moves immediately to ajoining station where it is brought together with the other adherand towhich it is to be joined. The joining station then nips the adherandstogether to form a bond.

[0326] The adhesive compositions according to the present inventionallow the adhesive to be applied to the adherand(s) prior to theadherand(s) entering the manufacturing line. For example, the adhesivecompositions according to the present invention may be applied at thepart supplier's facility with on-demand bonding occurring for, example,days, weeks, or months later, by RF activation.

[0327] Referring now to FIG. 38, a step and repeat manufacturing processas applied to a continuous production line 3802 with base adherand 3806and top adherand 3808 being supplied to bonding system 2000 on aconveyor system 3804. In one embodiment, base adherand 3806 ispre-coated with an adhesive composition 3805 according to the presentinvention. Base adherand 3806 could have been coated minutes, days,weeks, or months prior to base adherand 3806 entering continuousproduction line 3802. Base adherand 3806 travels along the conveyor 3804and top adherand 3808 is assembled to base adherand 3806 by hand orautomatic system (not shown). The assembled adherands 3810 are placedonto a pressure plate 2010 in which probes 2006 and 2008 are embedded.The bonding process begins when an electromagnetic field is createdbetween probes 2006 and 2008 by power supply 502. The electromagneticfield activates the adhesive composition 3805, which then creates a bondbetween adherands 3806 and 3808. Pressure plate 2020 is used to nip thebond during and/or after RF activation. After the bond is nipped, theassembly 3810 is removed from bonding system 2000 and placed back on theconveyor 3804.

[0328]FIG. 39 illustrates an index table bonding system. Index tablebonding systems are used in many manufacturing industries to automatethe bonding process. Examples include the bonding of labels ontobottles. The index table process allows for setting up multiple stationswhere different processes in the assembly process are performed. Thetime the index table stops at each station is the same, thus it isdependent upon the slowest process. An advantage of using an adhesivecomposition according to the present invention includes thepre-application to one or both of the parts to be bonded prior toloading the parts onto the index table. Other advantages are fastactivation and curing time. Consequently, by removing the adhesiveapplication from the index table, one less station is used and a higherproduction throughput is achieved.

[0329] Referring now to FIG. 39, an index table bonding system isdescribed. The index table bonding system includes an index table 3902,which is generally round and rotates either clockwise orcounter-clockwise. Base parts3904(1)-(N) having a pre-applied adhesivecomposition 3906 are placed onto index table 3902. When index table 3902moves base part 3904(1) to the next station (station 2), a top part 3908is placed onto base part 3904 to form assembly 3910. Assembly 3910 thenmoves to station 3 where it is exposed to an RF field, which activatesadhesive composition 3906. In station 3, the RF field is generated byprobes (not shown) positioned so that adhesive composition 3906 isactivated. The probes may be configured to either contact the assembly3910 and apply some pressure to aid in the bonding process.Alternatively, the probes could be configured so there is no contactwith the assembly 3910. After activation of the adhesive 3906, theassembly 3910 moves to station 4 for a nip or cure portion of thebonding process. After station 4, the assembly 3909 moves to station 5where it is unloaded from the index table 3902.

[0330]FIG. 21 illustrates a dynamic bonding system 2100 (also referredto as an in-line bonding system) for bonding or adhering adherands.Bonding system 2100 is referred to as dynamic because the adherands tobe adhered, adherands 2110 and 2112, continuously move through anelectromagnetic field; which is generated by heating system 2140. In oneembodiment, adherand 2110 is pre-coated with a composition 2104according to the system shown in FIG. 18.

[0331] Bonding system 2100 includes a roll 2102 of coated adherand 2110and plurality of rollers 2120, 2122, 2124, 2126, and 2128 for, amongother things, continuously guiding coated adherand 2110 and adherand2112 through an electromagnetic field generated by heating system 2140.In one embodiment, coated adherand 2110 and adherand 2112 move throughthe electromagnetic field at a rate of about 0.01 to 2000 feet perminute, most preferably, about 1000 feet per minute (ft/minute).

[0332] The bonding process begins when coated adherand 2110 is fed ontoroller 2120. Coated adherand 2110 is then passed over roller 2122. Apressure activated construction bond may be formed by passing the twoadherands 2110 and 2112 between roller 2122 and nip roller 2124. Aconstruction bond may be required in this process to maintain the properlocation of coated adherand 2110 and adherand 2112 prior to and/orduring activation. Preferably, the composition 2104 is formulated toprovide a pressure sensitive tack when a construction bond is needed.Coated adherand 2110 and adherand 2112 are not limited to any particularthickness. As should be readily apparent to one skilled in the art, thesystem can be designed to accommodate any reasonable thickness ofadherand.

[0333] In this embodiment, the invention relates to a method fordynamically bonding a first adherand to a second adherand, comprising:

[0334] (1) creating an article of manufacture comprising the firstadherand, the second adherand, and a composition, the composition beingplaced between the first adherand and the second adherand, wherein thecomposition can be activated in the presence of an RF field;

[0335] (2) moving the article of manufacture along a predetermined path;

[0336] (3) generating along a portion of the predetermined path an RFfield having sufficient energy to activate the composition, wherein thecomposition is activated by its less than one second exposure to the RFfield.

[0337] In a preferred embodiment, the article passes through the RFfield at a rate of at least about one-thousand feet per minute. In amore preferred embodiment, the article passes through the RF field at arate of about 1000 feet per minute.

[0338] Referring now to FIG. 22, after the construction bond is formed,the construction bonded coated adherand 2110 and adherand 2112 arepassed through an RF field 2230, which is generated by heating system2140. FIG. 22 further illustrates heating system 2140 for use in dynamicbonding system 2100.

[0339] Heating system 2140 includes a power supply, such as power supply502, for generating an alternating voltage between terminal 612 andterminal 610. Connected to terminal 612 is a probe 2210, and connectedto terminal 610 is a probe 2220. The characteristics of probes 2210 and2220 are described above with reference to probes 602 and 604 and probes2006 and 2008. In one embodiment, probe 2210 has a distal section 2211,a center section 2212 and a proximal section 2213. Similarly, in oneembodiment probe 2220 has a distal section 2221, a center section 2222and a proximal section 2223. Preferably, center section 2212 is parallelwith center section 2222, and they both have a length of about 48 incheswhen the adherands 2110 and 2112 are traveling at about 1000 feet/minutein the direction indicated by arrow 2130. This configuration results inabout a preferred 240 millisecond dwell time. Dwell time refers to themaximum amount of time that any given point on adherands 2110 and 2112is positioned beneath (or over) probes 2210 and 2220 (i.e., within theactivation region). If the speed of the adherands 2110 and 2112 isincreased, the preferred dwell time can remain constant by increasingthe length of probes 2210 and 2212. For example, if it is desired forthe adherands 2110 and 2112 to move at a rate of about 2000 feet/minover probes 2210 and 2220, and the preferred dwell time is about 100milliseconds, then the minimum length of probes 2210 anc 2220 would beabout 40 inches. Although a preferred dwell time is 600 milliseconds,the dwell time can be increased to several minutes if desired byincreasing the length of probes 2210 and 2220, e.g., from about the 20inches to 20 feet, and/or decreasing the speed at which adherands 2112and 2110 travel over probes 2210 and 2220. Shorter probes are alsocontemplated, for example from about 0.25 inches to about 20 inches.

[0340] Preferably, probes 2210 and 2220 are positioned with respect tocoated adherand 2110 such that the composition that coats coatedadherand 2110 is beneath (or above) an activation region. The activationregion is the area between the center section 2212 and center section2222.

[0341] The frequency of the alternating voltage generated by powersupply 502 can range from the low Kilohertz to high Gigahertz range. Inone embodiment the frequency ranges between about 1 MHz to about 5 GHz,most preferably about 10 MHz and 15 MHz. The peak to peak level of thevoltage generated by power supply 502 may range from about 500 V to 20kV, most preferably about 1 to 15 kV. The composition 2104 will remainactivated as long as the RF energy is delivered.

[0342] After the adherands 2110 and 2112 pass over (or under) probes2210 and 2220 they are nipped by non-destructive nip rollers 2126 and2128, which assure that a good bond is created between adherand 2110 andadherand 2112. For optimal performance, the nip rollers 2126 and 2128apply pressure immediately after re-flow temperatures are achievedwithin the adhesive material. Additionally, nip roller 2126 and/or niproller 2128 may be cooled to remove thermal energy from the adherands.Upon cooling, the composition forms a strong bond between the adherands2110 and 2112. The bonded adherands can then be subsequently processedin accordance with a particular application.

[0343] There are a number of benefits of the above system. First, thesystem provides a finished bond in less than about one second ofactivation. Second, the activation process does not produce harmfulemissions or by-products that may interfere with the bonding of two thinfilms. Third, the activation only occurs in the activation region.

[0344] FIGS. 23-27 illustrate alternative designs for heating system2140. As shown in FIG. 23, curved probes 2310 and 2320 can be used inplace of straight probes 2210 and 2220. An advantage of curved probes2310 and 2320 is that the width 2390 of the activation region is greaterthen the distance 2311 between probes 2310 and 2320, whereas the widthof the activation region provided by probes 2210 and 2220 equals thedistance between center section 2212 of probe 2210 and center section2222 of probe 2220.

[0345] The heating system shown in FIG. 24 includes probe 2410 inaddition to probes 2210 and 2220. Probe 2410 is positioned betweenprobes 2210 and 2220. Probe 2410 is parallel with probes 2210 and 2220.Preferably, the distance (d) between probe 2410 and 2210 is equal to thedistance (d) between probe 2410 and probe 2220. Probes 2210 and 2220 areboth connected to the same output terminal of voltage supply 502,whereas probe 2410 is connected to the other output terminal. Anadvantage of the probe design illustrated in FIG. 24. is that itprovides a larger activation region. The width 2420 of the activationregion is greater than the distance (d) between any two of the probes.Based on the above description, one skilled in the art will recognizethat any number of probes can be used in heating system 2140, providedthat no two adjacent probes are connected to the same output terminal ofvoltage supply 502.

[0346] The heating system shown in FIG. 25 is similar in concept to theone shown in FIG. 24. A curved probe 2510 is placed between curvedprobes 2310 and 2320. Curved probes 2310 and 2320 are both connected tothe same output terminal of voltage supply 502, whereas probe 2510 isconnected to the other output terminal. Again, an advantage of theheating system shown in FIG. 25 is that it can provide a largeractivation region than the similar heating system shown in FIG. 23.

[0347]FIG. 26 illustrates another heating system. The heating systemshown in FIG. 26 includes two plates 2610 and 2620. Plate 2610 ispositioned above adherand 2110 and plate 2620 is positioned belowadherand 2112. Thus, composition 2104 travels between plates 2610 and2620. Plate 2610 is connected to output terminal 610 of voltage supply502, and plate 2620 is connected to output terminal 612 of voltagesupply 502. When voltage supply 502 is turned on, it generates anelectromagnetic field between plates 2610 and 2620, which is used toactivate composition 2104. FIG. 27 illustrates another perspective ofplates 2610 and 2620. As is apparent from FIG. 27, the width of theactivation region for this design is simply the width (W) of the plates.The center to center distance (d) between plate 2610 and plate 2620 canrange from 0.02 inches to 20 inches. In one embodiment, the distanceranges between 0.25 inches and 1.5 inches. The length (L) of coursedepends on the desired dwell time and the rate at which any given pointon adherand 2110 or 2112 travels between any two points along the lengthof one of the plates.

[0348] XI. Exemplary Specific Applications of the Present Invention

[0349] The susceptor compositions may be employed for many purposesincluding bonding, cutting, and coating. Thus, the susceptorcompositions may be employed for packaging applications, e.g. to bond oradhere cases or cartons as described in U.S. Pat. No. 5,018,337, butwith the additional step of RF activation. Applications for the RF curedthermoset compositions, which are illustrative only and not to beconsidered limiting of the scope of the present invention, include:

[0350] Coatings for conventional and spray applications on plastics,metals, wood etc.

[0351] Corrosion resistance coatings.

[0352] Industrial and protective coatings.

[0353] Top coats.

[0354] Automotive coatings.

[0355] Lamination of composites.

[0356] Laminating adhesives.

[0357] Bonding of structural composites.

[0358] Inks and decorative coatings.

[0359] Barrier coatings.

[0360] Additional applications are listed below, but are likewiseillustrative and not limiting of the scope of the present invention.

[0361] A. Manufacture of Flexible Packaging

[0362]FIGS. 28A and 28B illustrate one embodiment of a system for themanufacture of flexible packaging. Flexible packages are used for, amongother things, packaging foods. The system includes a system 2802 (seeFIG. 28A) for manufacturing an RF activated adhesive film 2815 and abonding system 2804 (see FIG. 28B) for bonding the adhesive film 2815 toanother film 2850.

[0363] Referring now to FIG. 28A, film manufacturing system 2802includes an extruding system 2810, a casting wheel 2814 a heating system2820, a stretching system 2830, and an optional film roller 2840. In oneembodiment, extruding system 2810 includes three extruders 2811, 2812,and 2813. An RF activated adhesive composition according to the presentinvention is first formulated into an extrudable resin (for example,ethylene vinyl acetate or other polymer based material is added to theadhesive composition) and then provided to extruder 2813 in a pellet orliquid form. Polypropylene or other like similar substance, such as butnot limited to ethylene vinyl acetate (EVA), is provided to extruder2811, and a sealing material is provided to extruder 2812. The output ofextruders 2811-2813 are cast into a film 2815 by casting wheel 2814.

[0364]FIG. 29 illustrates film 2815. As shown in FIG. 29, film 2815includes a first layer 2902 consisting of the sealing material, a secondlayer 2904, e.g., OPP and/or EVA and/or other similar substance, and athird layer 2906 consisting of the RF activated adhesive. Because film2815 includes an adhesive composition according to the presentinvention, film 2815 can be RF activated.

[0365] Referring back to FIG. 28A, film 2815 is provided to heatingsystem 2820. In one embodiment, heating system 2820 includes heaterrollers 2821 and 2822. The function of heating system is to heat thefilm to a temperature that allows the film to be stretched. After beingprocessed by heating system 2820, film 2815 is stretched by stretchingsystem 2830. In one embodiment, stretching system 2830 includes aplurality of stretch rollers 2831, 2832, 2833, 2834, and 2835 and atransverse stretcher 2837. Stretching system 2830 stretches film 2815both length and width wise. After being stretched, film 2815 may berolled up using film roller 2840. Alternatively, film 2815 can be cutand stacked after being stretched.

[0366] Referring now to FIG. 28B, bonding system 2804 is used to bondfilm 2815 with film 2850. In one embodiment, film 2850 is a 70 gaugeoriented polypropylene (OPP) film. Film 2850 is passed over a printwheel 2855 and then through oven 2857. A pair of nip rollers 2860 and2861 press film 2815 with film 2850 to form a construction bond and thusform a single multi-layer film 2870. FIG. 30 illustrates one embodimentof film 2870.

[0367] As shown in FIG. 30, film 2870 includes layer 2902 consisting ofthe sealing material, layer 2904 that includes thermoplastics and/orelastomers, for example, OPP and/or EVA and/or other similar substance,third layer 2906 consisting of the RF activated adhesive, a fourth layer3002 consisting of the ink applied by print wheel 2855, and a fifthlayer 3004 consisting of film 2850.

[0368] Referring back to FIG. 28B, an RF heating system 2875 creates anRF field that is used to heat adhesive layer 2906.Heating system 2875defines an activation region. The activation region is an area in whichthe RF field generated by heating system 2875 is strong enough toactivate adhesive layer 2906. Film 2870 can travel through theactivation region in as quickly as about 100 milliseconds. Shortly afterpassing through the activation region, film 2870 is nipped by niprollers 2880 and 2881 and then rolled by film roller 2885. FIGS. 16A and16B illustrate one embodiment of the probe portion of heating system2875. Other heating systems could be used, such as those described abovewith respect to FIGS. 20 and 21.

[0369]FIG. 31 illustrates an alternative system 3100 for manufacturingan RF activated adhesive film for use in the flexible packagingindustry. System 3100 is similar to system 2802, except that system 3100does not include extruder 2813. In place of extruder 2813, system 3100includes an adhesive applicator 3101 and a heating system 3102. Anadhesive composition according to the present invention is formulatedinto a liquid dispersion and applied to film 2815 by adhesive applicator3101. In one embodiment adhesive applicator 3101 includes a gravureapplication tool (not shown). Heating system 3102 can be a conventionalheating system, such as an oven, or it can be an RF heating system, suchas heating system 600 or any of the other heating systems describedherein.

[0370] B. Food Packaging and Cap Sealing

[0371] Conventionally, metallic foils are used as susceptors ofelectromagnetic energy to generate heat for package sealing. Typicalexamples include tamper evident bottle seals (i.e., cap sealing) andfood packaging. While the conventional systems are effective in sealingthe packages, the use of metallic foils eliminates the manufacturer'sability to perform post sealing inspection, such as metal detection,x-ray, and the like. Additionally, there may be a recycling benefit anda cost saving to the system by eliminating the metallic foil.

[0372] One solution is to replace the metallic foil with a compositionof the present invention. The composition may or may not have adhesiveproperties. FIG. 32 illustrates a conventional aseptic packageconstruction. A conventional aseptic package includes an outerpolyethylene layer 3202, a paper layer 3204, a second polyethylene layer3206, a layer of metallic foil 3208, a third 3210 polyethylene layer, aninner polyethylene layer 3212, and a container 3214 that holds the foodor beverage. Inner polyethylene layer 3212 is the layer that contactswith the container 3214, and is used to seal the container during thefood packaging process. The sealing is achieved through inductionheating of the metallic foil layer 3208 causing the inner polypropylenelayer 3212 to melt and bond to the container 3214.

[0373]FIG. 33 illustrates one embodiment of a packaging constructionthat does not use metallic foils. The packaging construction includesthe outer polyethylene layer 3202, the paper layer 3204, the secondpolyethylene layer 3206, a susceptor composition according to thepresent invention 3302, a barrier layer 3310, an inner layer 3212, and acontainer 3214 that holds the food or beverage. Inner layer 3212 is thelayer that contacts with the container 3214, and is used to seal thecontainer 3214 during the food packaging process. Inner layer 3212 canbe a polyethylene or EVA layer. In one embodiment, barrier layer 3310 isan EVOH barrier layer. The sealing is achieved through RF heating ofsusceptor composition 3302, which causes the inner layer 3212 to meltand bond to the container 3214. The advantage of replacing metallic foil3208 with susceptor composition 3302 is that now the container 3214 canbe inspected after it is sealed by using a metal detector or x-raymachine, and there are recycling advantages as well.

[0374] A conventional cap sealing construction is illustrated in FIG.34. FIG. 34 illustrates a polyethylene bottle 3402, a seal 3401, and abottle cap 3414. Seal 3401 includes several layers of substrate,including a polyethylene layer 3404, a metallic foil layer 3406, anotherpolyethylene layer 3408, a wax layer 3410, and a paper layer 3412. Seal3401 is adhered to bottle 3402 by heating foil through induction, whichcauses layer 3404 to weld to bottle 3402. As discussed above, it isdesirable to remove metallic foil layer 3406.

[0375]FIG. 35 illustrates an improved seal 3501 for bottle 3402. Seal3501 is identical to seal 3401 (see FIG. 34), except that the metallicfoil 3406 has been replaced with a composition 3502 according to thepresent invention. As discussed above, the advantage of removingmetallic foil 3406 is that now bottle 3402 can be inspected after it issealed by using a metal detector or x-ray machine, and can be moreeasily recycled.

[0376] Another use of the compositions described herein is to attach aflexible bag 3602 containing dry food to an outer box 3604, asillustrated in FIG. 36. In one embodiment, flexible bag 3602 includesthree layers, 3610, 3611, and 3612, and outer box 3604 is a paperproduct, such as a paper board. To bond flexible bag 3602 to outer box3604, an adhesive composition 3620 according to the present invention isplaced between outer box 3604 and layer 3610. Adhesive composition 3620is then exposed to an RF field that causes the composition 3620 to meltand flow and bond layer 3610 to outer box 3604. In one embodiment, layer3610 is a polyethylene layer, layer 3611 is an EVOH barrier layer, andlayer 3612 is an EVA food contact layer. In another embodiment (see FIG.37), outer box 3604 is coated with a polyethylene layer (or other likelayer) 3730. This configuration creates an improved bond.

[0377] C. Printing Applications

[0378] The susceptor compositions of the present invention may also beapplied together with one or more inks to provide writing, a design orgr aphic, e.g. as is described in U.S. Pat. No. 4,595,611. Particularapplication of this aspect of the invention is in the preparation ofink-printed substrates such as ovenable food containers. Examples ofpigments that can be combined with the susceptor composition includetitanium dioxide, iron oxide pigments, carbon black and organic pigmentssuch as isoindoline yellow. In a preferred embodiment, the susceptor isa sulfonated polyester. Alternatively, a sulfonated polyester-cationicdye salt may be employed as disclosed in U.S. Pat. No. 5,240,780. Thesubstrate may be printed once or multiple times to achieve the desiredresult. Once printed, the substrate may be further coated with a clearunpigmented composition which may comprise the susceptor composition ofthe invention. The same composition used to print may be used to furthercoat, but without the added pigments. The susceptor compositions may beRF activated after each printing/coating step, or after all of thecoatings are applied. Finally, the substrate may be coated with a clearpolyester sealing resin.

[0379] An extension the printing application is high speed ink-jet usedin printers/copiers. Inks formulated as liquids (H-P/Cannon) or solid(Tetronic) composition can contain the susceptor compositions of thisinvention in amounts effective that can be activated by RF energy forrapid drying and fixing. Current ink formulations are too “slow indrying” or need excessive heat energy.

[0380] D. Bookbinding and Mailers

[0381] The susceptor compositions of the present invention may be usedto bond paper substrates used in printing and/or copying. An advantageof the present invention is that a substrate to be printed on (such as apaper substrate) can be coated with a susceptor composition describedherein prior to printing on the substrate. For example, FIG. 43illustrates a process for assembling a book, magazine, or periodical, orthe like. In step 4302, a portion of one side of a substrate is coatedwith a susceptor composition that functions as an adhesive. Any one ofthe various methods for coating a substrate described herein can be usedto coat the substrate. FIG. 44 illustrates a preferred portion of asubstrate to be coated with the susceptor composition. As shown in FIG.44, a thin strip of the susceptor composition 4404 coats one edge of thesubstrate 4402. The portion of the substrate that is not coated is theportion where ink will be printed. Preferably, the susceptor composition4404 is formulated such that it is tack free, however, this is not arequirement.

[0382] After the substrate 4402 has been coated, the substrate may beprocessed into rolls, stacks and the like and stored for later use (step4304). In step 4306, the coated substrate is fed into a printing meansthat prints ink onto the substrate. The printing means can be aconventional printer or conventional photocopying machine. Further, thesubstrate can be fed into the printing means as a continuous substrateor as cut pieces. For this example, we will assume that cut pieces ofthe substrate are fed into the printing means. In step 4308, after theprinting means prints ink onto a substrate, the substrate is stackedwith the other substrates that have already been fed into the printingmeans as shown in FIG. 45. The stack is placed in an electromagneticfield. The electromagnetic field causes the susceptor composition tomelt and flow. The stack is then nipped to assure a good bond (step4312).

[0383] In one embodiment, prior to placing the stack in theelectromagnetic field, the substrate stack is pressure bonded byapplying upward and/or downward pressure on the stack. In anotherembodiment, the ink that is printed on the substrates includes asusceptor composition. In this way, the ink can be dried rapidly bypassing the substrate through an electromagnetic field.

[0384] In another embodiment, mailers or envelopes can be constructed.Referring to FIG. 46, a portion of one side of substrate 4602 is coatedwith a susceptor adhesive composition 4604. Preferably, the susceptoradhesive composition 4604 is formulated so that it is tack-free. Thesubstrate 4602 includes a fold line 4610. The coated substrate 4602 canbe fed into a printing means that prints ink onto the substrate. Afterthe ink is printed thereon, the substrate is folded along the fold line4610 so that-the top portion 4612 of the substrate 4602 contacts thebottom portion 4614 of the substrate (see FIG. 47). At this point, thesubstrate is passed through the electromagnetic field so as to melt andflow the susceptor composition 4604, thereby bonding the top portion4612 of the substrate with the bottom portion 4614 when the susceptorcomposition 4604 solidifies.

[0385] E. Security Devices

[0386] As would be apparent to one skilled in the relevant art(s), theadhesive of the present invention can be used to seal containers,casings, housings and the like (hereafter “container”). In particular,the adhesive of the present invention is preferably used to sealcontainers that a manufacturer does not want accessed by others. Amanufacturer may want to prevent a third party from opening certaincontainers for security, safety or quality control reasons. However, theinside of the container must still be accessible to the manufacturer orqualified repair facility. By exposing the seal to an electromagneticfield, the manufacturer can disassemble the container.

[0387] For example, a manufacturer may want to prevent an articleintended for one-time use from being reused. As such, the adhesive ofthe present invention can be used, for example, to seal the shell orcasing of a disposable camera. The manufacturers of such disposablecameras often do not want to have the shells reloaded and reused by theconsumer or a competitor company. If the adhesive of the presentinvention is used to seal the camera shell, then when the film developeropens the camera body to remove and process the film, mating sections ofthe camera shell attached by the adhesive would break or deform suchthat the camera body could not be reused. As such, the adhesive of thepresent invention would prevent tampering with and unauthorizedreloading of disposable camera shells.

[0388]FIG. 48 shows an example of a container 4800 sealed with asusceptor composition of the present invention. Container 4800 includesa first portion 4804 and a second portion 4808. In one embodiment, firstportion 4804 is a container base and second portion 4808 is a lid.Container 4800 can be made from a variety of materials, including, forexample, polypropylene, polystyrene, polyolefin, wood or wood products,rubber, plastics, glass, ceramics, paper, cardboard, natural orsynthetic textile products, aluminum or other foils, metals, or anycombination of these materials. An adhesive composition 4812, made inaccordance with the present invention, is applied to a surface ofcontainer 4800. In the example of FIG. 48, adhesive composition 4812 isapplied to a first mating surface of first portion 4804. Second portion4808 is then placed on top of first portion 4804, so that a secondmating surface of second portion 4808 comes in contact with adhesivecomposition 4812. A suitable electromagnetic field, as described herein,is then applied to adhesive composition 4812 to join the first andsecond mating surfaces of first and second portions 4804 and 4808.

[0389] To open container 4800, suitable RF energy must again be appliedto container 4800 to cause adhesive composition 4812 to reflow. If aperson attempts to open container 4800 without applying the suitableelectromagnetic field, the container 4800 is designed to preferablybreak or catastrophically fail and so that it cannot be reused.

[0390]FIG. 49 shows another example of a device 4900 sealed or otherwisejoined together with a composition of the present invention. Device 4900includes a first portion or substrate 4904 and a second portion orsubstrate 4908. Device 4900 can be made of a variety of materials, asdiscussed above with respect to container 4800, shown in FIG. 48. Inthis embodiment, first substrate 4904 includes a male portion 4912forming the first mating surface. Male portion 4912 includes a narrowedsection 4916 and a wider section 4920. A corresponding female portion4924 forming a second mating surface is formed in second portion 4908and is configured to accommodate or receive wider section 4920 of maleportion 4912. Second portion 4908 may also be configured to accommodatea portion of narrowed section 4916.

[0391] An adhesive composition 4928, made in accordance with the presentinvention, is applied to the second mating surface of female portion4924 of second portion 4908. First portion 4904 is then assembled sothat the first mating surface comes in contact with adhesive composition4928 on second portion 4908 while the adhesive composition is within theelectromagnetic field. First portion 4904 is locked into second portion4908 once the application of electromagnetic filed is discontinued,causing adhesive composition 4928 to solidify. To disassemble device4900, an electromagnetic field must again be applied to adhesive 4928 tocause it to reflow and allow the portions 4904 and 4908 to separate. Ifsomeone attempts to disassemble device 4900 without application of asuitable electromagnetic field, narrowed section 4916 of male portion4912 will break or otherwise catastrophically fail resulting in device4900 being unusable. As such, this embodiment will prevent authorizeddisassembly and reuse of device 4900.

[0392]FIG. 50 shows another example of a device 5000 sealed or otherwisejoined together with a composition of the present invention. Device 5000is similar to device 4900 described above with respect to FIG. 49,except that an electronic circuit path 5004 is added to male portion4912 such that it is disposed through narrowed section 4916. As such,should portions 4904 and 4908 of device 5000 be disassembled withoutapplication of a suitable electromagnetic field, electronic circuit path5004 will be cut during failure of narrowed section 4916, resulting infurther failure of device 5000.

[0393]FIG. 51 shows still another example of a cross-section of acontainer 5100 that has been sealed with the adhesive of the presentinvention. Container 5100 includes a first portion 5104 and a secondportion 5108. Container 5100 can be made of a variety of materials, asdiscussed above with respect to container 4800, shown in FIG. 48. Firstportion 5104 includes a protrusion 5112 which forms a first matingsurface. In the embodiment shown in FIG. 51, protrusion 5112 extendsaround the entire circumference of container 5100.However, it would beapparent to one skilled in the relevant art that one or more discreteprotrusions 5112 could be used instead of or in addition to thecontinuous protrusion 5112. Second portion 5108 includes a recess 5116which forms a second mating surface corresponding to the first matingsurface of protrusion 5112. Protrusion 5112 and corresponding recess5116 are formed slightly inward of the periphery of container 5100 to sothat when first and second portions 5104 and 5108 are joined, the matingsurfaces and an adhesive composition 5120 therebetween cannot beaccessed, thereby further reducing the risk of a person prying apart orotherwise disassembling container 5100. Adhesive composition 5120, madein accordance with the present invention, is applied to the secondmating surface of recess 5116. First and second portions 5104 and 5108can be joined together by application of suitable electromagnetic fieldand similarly disassembled by re-application of the electromagneticfield.

[0394] The invention relates to an apparatus, comprising:

[0395] a first portion having a first mating surface;

[0396] a second portion, having a second mating surface;

[0397] a composition disposed between the first mating surface and thesecond mating surface, wherein the composition comprises a susceptor anda polar carrier wherein the susceptor and/or the polar carrier arepresent in amounts effective to allow the composition to be heated by RFenergy, and wherein the composition adheres the first mating surface tothe second mating surface such that application of a force to separatethe first mating surface and the second mating surface results inbreakage of the apparatus unless the composition is in a melted state.

[0398] In this apparatus, the composition may be disposed on the firstmating surface and the second mating surface such that the compositionis not accessible when the first and second mating surfaces are joined.In another embodiment, the first mating surface may comprise aprotrusion disposed on the first portion. In another embodiment, thesecond mating surface may comprise a recess formed in the secondportion. In a further embodiment, the apparatus may further comprise anelectronic circuit path disposed in the protrusion. In anotherembodiment, the first portion and the second portion are disassembledupon application of an electromagnetic energy to the composition.

[0399] F. Thermal Destruction

[0400] The susceptor composition of the present invention can not onlybe used to coat a substrate and bond adherands, but also can be used tocut a substrate. A substrate can be cut using a susceptor compositiondescribed above by first applying the susceptor composition to at leastone side of the substrate. Next, an electromagnetic field is applied tothe susceptor composition causing the susceptor composition to heat. Thethermal energy generated by the susceptor composition heats thesubstrate, particularly the section of the substrate that is in contactwith the susceptor composition. The substrate is heated until a sectionof the substrate melts resulting in the substrate being cut.

[0401] In this embodiment, the invention relates to a method for cuttinga substrate, comprising:

[0402] applying a composition to a portion of the substrate, wherein thecomposition comprises a susceptor and polar carrier wherein thesusceptor and/or the polar carrier are present in amounts effective toallow the composition to be heated by RF energy, and wherein the portionof the substrate defines a first section of the substrate and a secondsection of the substrate;

[0403] melting the portion of the substrate, wherein the melting stepincludes the step of heating the composition, wherein the step ofheating the composition includes the step of applying RF energy to thecomposition;

[0404] after the portion of the substrate has begun to melt, applying aforce to the substrate to separate the first section from the secondsection.

[0405] G. Seam Sealing

[0406] The susceptor compositions of the present invention may be usedto seal the seams of products made from cloth. Conventional clothmaterials manufactured from man made or natural fibers are sewn togetherto form cloth products, such as clothing, bags, tents, awnings, covers,and the like. Typically, the seams of cloth products such as tents,awnings, bags, etc. need to be sealed to prevent leakage of liquidsthrough the small holes in the products created by a sewing needle andthread during a stitching process. The susceptor compositions of thepresent invention can be used to seal these seams.

[0407]FIG. 62 illustrates how a susceptor composition of the presentinvention can be used to seal the seams of cloth products. FIG. 62illustrates a seam sealing system 6200 for sewing a first cloth material6202 to a second cloth material 6204 and for sealing the seam. In oneembodiment, a susceptor composition 6206 according to the presentinvention is placed between the first and second cloth materials 6202and 6204. In another embodiment, either one or both of the clothmaterials 6202 and 6206 are coated with the composition in the locationwhere the seam will exist.

[0408] The system includes a pressure plate 6208 and a reciprocatingneedle 6212, through which a thread 6210 can be threaded, for joiningthe first cloth material 6202 with the second cloth material 6204. Theseam sealing system 6200 also includes an RF heating system according tothe present invention for activating the composition 6206. The RFheating system includes a reciprocating pressure foot 6214 and at leasttwo probes (not shown) placed within and near the surface of thepressure plate 6208. The probes (not shown) are connected to the powersupply 502 for generating an RF field at the probes. Alternatively, theprobes can be located within the pressure foot 6214 as opposed to thepressure plate 6208.

[0409] The cloth materials 6202 and 6204 and the composition 6206 arepulled past the reciprocating needle 6212 and then past thereciprocating pressure foot 6214. The reciprocating needle 6212 andthread 6210 stitch the first material 6202 to the second material 6204,thereby joining the materials together at a seam. This stitching processcreates small holes in the materials 6202 and 6204. The RF fieldgenerated at the probes within the pressure plate 6208 activates thecomposition 6206, which causes the composition 6206 to flow and therebyfill or cover the small holes created by the needle 6212 during thestitching process. The reciprocating pressure foot 6214 functions toevenly flow the activated composition 6206, thereby facilitating thecomposition in the filling/covering of the holes created by the needle6212. In this manner, the susceptor compositions of the presentinvention can be used to seal seams.

[0410] XII. Kits

[0411] The invention also provides kits for use in the preparation ofthe bonding composition according to the present invention. Kitsaccording to the present invention comprise one or more containers,wherein a first container contains a susceptor composition of theinvention. Additional kits of the invention comprise one or morecontainers wherein a first container contains a susceptor as describedabove and a second container contains one or more adhesive compoundsand/or carriers, such as water, glycerine, N-methyl pyrrolidone (NMP),dimethylformamide (DMF), dimethylacetamide (DMAC), dimethylsulfoxide(DMSO), tetrahydrofuran (THF), polyvinyl pyrrolidone (PVP),polyvinylpyrrolidone/vinyl acetate copolymer (PVP/VA), and branchedpolyesters. The kits of the invention may be used to produce one or moreof the bonding compositions of the present invention for use in avariety of applications as described below.

[0412] The invention also provides for kits comprising at least twocontainers, wherein one of the containers comprises a susceptor andanother of the containers comprises a polar carrier, wherein when thesusceptor and the carrier are applied to substrates and the appliedsusceptor and carrier are interfaced, a composition is formed that isheatable by RF energy.

[0413] XIII. Experimental Set-Up

[0414]FIG. 40 shows an example experimental set-up utilized to test thesusceptor compositions described above with respect to example 4. An RFsignal is generated by a signal generator 4001. Signal generator 4001can be an HP 8165A signal generator (available from Hewlett PackardCorporation). The RF signal is coupled to the input side of RF poweramplifier 4002 (available from ENI). The RF power is fed from the outputside of RF power amplifier 4002 to the input side of an impedancematching circuit 4003 that functions to match the output impedance tothe combined load impedance of coil 4004 and test sample 4005. Impedancematching circuit 4003 can be designed according to known electronicsprinciples as would be apparent to those of skill in the art. See, e.g.,“The Art of Electronics,” by P. Horowitz and W. Hill, Second Ed.,Cambridge University Press (1994), especially Chapter 40, incorporatedby reference herein. The RF power of load coil 4004 was inductivelycoupled to test sample 4005. The frequency of signal generator 4001 wastuned to result in resonance at load coil 4004. This frequency wasdetected by a single turn, 2 inch diameter probe loop 4007, which waslocated just below and in proximity to load coil 4004. Resonance wasindicated by a maximum resulting voltage drop across probe loop 4007,and was displayed on an oscilloscope 4006, such as a model numberOS7020A oscilloscope available from Goldstar. Frequency tuning wasperformed at sufficiently low RF powers in order to avoid heating oftest sample 4005. Once the frequency of signal generator 4001 was tunedto resonance, the RF power delivered to load coil 4004 was increased toa desired power level by increasing the output level of signal generator4001. The front panel of RF power amplifier 4002 displayed the measuredRF power level delivered to test sample 4005.

[0415]FIG. 41 illustrates another experimental heating system4100.Heating system 4100 includes a signal generator 4102. Signalgenerator 4102 can be an HP 8165A signal generator (available fromHewlett Packard Corporation). Signal generator 4102 is used to generatea low level radio frequency signal having a frequency between 10 MHz and15 MHz. Signal generator has a control panel 4103 that allows a user tomanually select the frequency of the generated radio frequency signal.The output level of the signal is also controllable from control panel4103, or from a controller 4114. The output level of the generated RFsignal can vary from 0 Volts to 1 Volt peak to peak into 50 ohms, or 0dBm.

[0416] Controller 4114 is interfaced to signal generator through ageneral purpose interface board (GPIB) (not shown). In one embodiment,controller 4114 is a personal computer (PC) running the Windows®operating system. A visual C++ program that provides a user interfacefor controlling the output level of signal generator 4102 is configuredto run on controller 4114.

[0417] The low level RF signal generated by signal generator 4102 isprovided to the input of a broadband RF amplifier 4106 using a coaxialcable 4104. Preferably, broadband RF amplifier 4106 is the A 1000broadband amplifier sold by ENI of Rochester, N.Y., and coaxial cable4104 is a standard RG58 coaxial cable. Broadband Amplifier 4106amplifies the low level RF signal by 60 dB, thereby providing a 1Kilowatt output into a 50 ohm load for a 1 milliwatt (0 dBm) input. Ifthe low level RF input signal provided to amplifier 4106 consists of atimed pulse, amplifier 4106 will amplify the pulse to produce a highlevel pulse output.

[0418] Connected to the output of broadband amplifier 4106 is adirectional coupler 4110. A suitable directional coupler can bepurchased from Connecticut Microwave Corporation of Cheshire, Conn.Directional coupler 4110 is connected to the output of amplifier 4106through an RF cable 4107, such as an RG393 RF cable. The output ofdirectional coupler 4110 is connected to an impedance matching circuit4122 using RG393 RF cable 4112.

[0419] The function of impedance matching circuit 4122 is to match a 50ohm input impedance to a variable impedance of probes 602 and 604 andthe sample 410. Typical impedances of probes 602 and 604 in combinationwith sample 410 range from 200 ohms up to 500 ohms.

[0420] Directional coupler 4110 has a reflected power output port 4111that is connected to an oscilloscope 4118. Preferably, oscilloscope 4118is a TDS210 digital real time oscilloscope available from Tektronix,Inc. Directional coupler 4110 provides a signal representing the amountof reflected power to oscilloscope 4118, which then displays themagnitude of the reflected power.

[0421] The process for heating sample 410 using heating system 4100 willnow be described. Initially, an operator interacts with a user interfaceon controller 4114 to activate signal generator 4102 so that it producesa 50 millivolt RF signal. The reflected power is then observed onoscilloscope 4118. The frequency of the 50 millivolt RF signal andmatching circuit 4122 are adjusted such that the reflected power isminimized. Once the frequency and the matching circuit are adjusted suchthat the reflected power is minimized, the signal generator is turnedoff and sample 410 is placed close to probes 602 and 604.

[0422] Next, controller 4114 is used to turn on signal generator 4102 sothat it once again produces a 50 millivolt RF signal. At this point, thefrequency and matching circuit are adjusted again until the reflectedpower is minimized. On achieving the minimum reflected power, signalgenerator 4102 is turned off. Next, operator uses controller to directsignal generator to produce an RF signal with a voltage ranging from 100millivolts to 1000 millivolts and with a pulse time of between 20milliseconds and 1000 milliseconds. This low level RF signal isamplified by broadband amplifier 4106. The amplified signal is thenprovided to impedance matching circuit 4122 and an a RF pulsedelectromagnetic field is produced at probes 602 and 604. The presence ofthe pulsed electromagnetic field causes sample 410 to heat.

[0423]FIG. 42 illustrates probes 4202 and 4204, which were the probesutilized to test the compositions described herein. The presentinvention is not limited to this or any particular probe design. Probe4202 and probe 4204 are both {fraction (1/8)} inch square copper tubes.Probe 4202 and probe 4204 both rest on a block 4250 of non-electricallyconductive material, preferably, but not limited to, TEFLON™. Morespecifically, block 4250 has {fraction (1/8)} inch square slots milledtherein so that probes 4202 and 4204 are recessed into block 4250.

[0424] Probe 4202 has a proximal section 4209, a center section 4210, atransition section 4211, and a distal section 4212. Similarly probe 4204has a proximal section 4213, a center section 4214, a transition section4215, and a distal section 4216. Center section 4210 is parallel withcenter section 4212. The center to center distance between centersection 4210 and center section 4212 is on half of an inch.

[0425] Proximal section 4209 diverges away from probe 4204. Similarly,proximal section 4213 diverges away from probe 4202. The center tocenter distance between the proximal end of proximal section 4209 andthe proximal end of proximal section 4213 is about at least one andthree sixteenths of an inch.

[0426] Distal section 4212 is parallel with distal section 4216 andparallel with center section 4210. The center to center distance betweendistal section 4212 and distal section 4216 is about at least one andthree sixteenths of an inch. Transition section 4211 is between centersection 4210 and distal section 4212. Similarly, transition section 4215is between center section 4214 and distal section 4216.

[0427] The reason the distance between the proximal end of proximalsection 4209 and the proximal end of proximal section 4213 is about atleast one and three sixteenth of an inch is to prevent arcing at theends of probe 4202 and 4204. For that same reason the distance betweendistal section 4212 and distal section 4216 is about at least one andthree sixteenth of an inch.

[0428] XIV. Examples

[0429] Without further elaboration, it is believed that one skilled inthe art can, using the preceding description, utilize the presentinvention to its fullest extent. The following preferred specificembodiments are, therefore, to be construed as merely illustrative andnot limitative of the remainder of the disclosure in any way.

Example 1

[0430] Various susceptor compositions were screened for use atfrequencies from about 4 MHz to 15 MHz, and at power levels from about0.5 kW to 1 kW. RF frequencies of less than about 15 MHz are much lesscostly to produce and operate than RF frequencies of greater than 15MHz. The best results consistently occurred at the upper ends of theexperimental frequency and power ranges (e.g., 15 MHz and 1 kW). SeeFIG. 6 for a schematic diagram of the experimental set-up and equipmentused for the various tests described herein. According to the presentinvention, a preferred composition comprises a uniform solution of PVP,NMP, and SnCl₂. A suitable susceptor composition comprises SnCl₂ presentin a concentration of from about 1% to about 50%, NMP in a concentrationof from about 25% to about 75%, and PVP in a concentration of from about1% to about 35%. These three components are soluble in one another.These components were mixed together to form a uniform solution that wasable to be heated from about 75° F. to a boiling point of about 280° F.in several seconds. Acceptable results can also be obtained, forexample, by substituting similar concentrations of PVP/vinyl acetatecopolymer for PVP, and substituting similar concentrations of lithiumperchlorate for SnCl₂. In addition, other suitable compositions includea mixture comprising ethylene/vinyl acetate copolymer in a concentrationof from about 75% to about 99% and ethylene/acrylic acid copolymer in aconcentration of from about 1% to about 25%, a mixture comprisingLiC₂H₃O₂ in a concentration of from about 1% to about 25%,ethylene/vinyl acetate copolymer in a concentration of from about 50% toabout 98%, and styrenated ethylene/acrylic acid copolymer in aconcentration of from about 2% to about 25%, and a mixture comprisingPVP/vinyl acetate copolymer in a concentration of from about 5% to about35%, SnCl₂ in a concentration of from about 5% to about 49%, and NMP ina concentration of from about 1% to about 90%. Other compositionconstituent concentrations will be apparent to those of skill in the artbased on the present description.

[0431] In this example, a preferred susceptor composition comprisingSnCl₂ in a concentration of about 33%, NMP in a concentration of about50%, and PVP in a concentration of about 17% was prepared to bondvarious combinations of thin polyolefin layers of polypropylene (PP) andpolyethylene (PE). This example susceptor composition resulted in auniform dispersion of salt ions in a polymeric adhesive.

[0432] The experiment was conducted by saturating a second carrier, athin layer of an insoluble porous carrier (in this example non-wovenPP), with a small amount of the susceptor composition. The examplesalt-based susceptor composition provides a continuous matrix of saltions in a polar organic medium throughout the insoluble porous carrier.As shown schematically in FIG. 3, the insoluble porous carrier 302 wassandwiched in-between two layers of PP or PE, layers 304 and 306,respectively, and then transversely heated by the application of RFenergy. By RF heating at about 14-15 MHz for about 1-2 seconds at about0.8-1 kW of power output, sufficient bonding occurred between thenon-woven PP carrier and the layers of PP and PE. In this example, thestrength of the bonded region was at least as strong or stronger thanthe PP or PE substrates themselves. The polyolefin layers to be bondedwere chosen from combinations of (1) PP non-woven and (2) PE film. Theresults of this example are shown below in Table 1. TABLE 1 insolubleporous carrier (saturated with PVP, NMP and SnCl₂) bonding results PPnon-woven/PP non-woven bonding within 1-2 seconds PE film/PE filmbonding within 1-2 seconds PP non-woven/PE film bonding within 1-2seconds

[0433] For each combination, the saturated insoluble porous carrierbonded the outer layers in about 1-2 seconds. There was evidence ofmelting in the outer layers, with some minor substrate distortion andtiny melt holes. By using the saturated PP non-woven carrier, a uniformmatrix of the adhesive and susceptor components resulted in intimatecontact between the adhesive component and both outer layers.

Example 2

[0434] The susceptor composition utilized in this example comprisedSnCl₂ in a concentration of about 33%, dissolved in a mixture of NMP ina concentration of about 50% and PVP in a concentration of about 17%.Various PP and PB substrate surfaces were coated with the RF susceptorcomposition, including: (1) PP non-woven and (2) PE film. The susceptorcomposition was hand drawn onto each surface as a wet layer that wouldeventually dry, leaving a coating which was dry to the touch. RF heatingtests were performed on the coated substrates. In each case, two likesamples were placed together with the coated surfaces in contact withone another. The contacted surfaces were placed in a load coil that wasdesigned to clamp the surfaces firmly together and transversely heat a0.25 inch×8 inch strip of the susceptor composition. The operatingfrequency was about 14 MHz, and the power delivered to the coil wasabout 1 kW. The tests were split into two parts: using a wet susceptorcomposition and using a vacuum dried susceptor composition. The resultsare shown in Table 2.

[0435] Vacuum drying was employed in this experiment as an extremeexperimental condition for comparison purposes, but is not expected torepresent a commercial embodiment. TABLE 2 Coated Substrates in Contact,Under 1.2 kW RF at 14 Mhz WET/DRY non-woven PP/ PE film/ Substratesnon-woven PP PE film WET successfully evidence of bonded togethermelting, slight within 1-2 seconds bonding at edges of the coat ofsusceptor material VACUUM No evidence of No evidence of DRIED heatingafter 1 heating after 1 minute. minute.

[0436] The results show that the wet susceptor composition generatesenough heat within 1-2 seconds at 14 MHz and 1 kW to melt the PPnon-woven or PE film in transverse heating of thin hand drawn films.Bonding is successful between layers of PP non-woven. As layers of PPnon-woven are brought together, the susceptor composition is displacedinto the open space between the fiber of the PP non-woven layers,allowing the two layers of PP non-woven to come together and makeintimate contact, enabling bonding during re-flow of the layers.

[0437] Complete bonding was not demonstrated between layers of PE film.As layers of PE film were brought together, the susceptor mixturebehaved as a hydrostatic middle layer or boundary, preventing intimatecontact between the two outer polyolefin layers. It was observed thatthe material in the layers of PE was more likely to partition away fromthe susceptor composition than to cross the susceptor composition layerduring melting and re-flow. It was also observed that as the susceptorcomposition was vacuum dried, it lost its ability to be RF heatedeffectively. Results were likely due to one or more of the followingfactors: the precipitation of ions back into an inactive salt as thesolvent volatilizes to form the dry coat; a decrease in translationalmobility of any ions still supported by the dry coating, thus preventingRF heating from occurring; and, in the case of PE films, an insufficientintermolecular contact due to the smoothness of the films. According tothe present invention, this problem can be solved by introducing anadditive, such as a surfactant, nonvolatile solvent or, plasticizer tothe composition, to achieve better attachment.

Example 3

[0438] In this example, an RF activated susceptor composition wasprepared from an EASTMAN AQ branched polyester (available from theEastman Chemical Corporation) and an aqueous solution of SnCl₂. Variouslayers of PP non-woven and PE film were tested. The susceptorcomposition that was used in this example comprised SnCl₂ dissolved indistilled water. This solution was blended with a branched polyesteradhesive component, EASTMAN AQ35S. Suitable concentrations of thebranched polyester ranged from about 25% to about 75%.

[0439] In a series of experiments, the susceptor composition was used toadhere all combinations of: (1) PP non-woven and (2) PE film substrates.In each experimental combination, the composition was first coated ontothe two substrate surfaces and dried under ambient conditions similar tothose used in commercial practice. The two substrates were then pressedtogether in the work coil with the two susceptor composition coatedsurfaces in contact with each other. The coated surfaces were not tackyenough at this point to result in contact adhesion between thesubstrates. All combinations of substrates were successfully adhered toone another by RF heating for a period of about 1 second at about 14 MHzand about 1 kW. The substrates were adhered to each other by theRF-activated susceptor composition, instead of being bonded by re-flowof the substrate. No apparent melting or distortion of the substrateoccurred. This example demonstrates that a susceptor composition coatingcan be dry to the touch and still be activated by RF heating.

Example 3a

[0440] Analogous to Example 3 above, the active ingredients EastmanAQ35S and SnCl₂ (in constituent concentrations consistent with theparameters described above) were dissolved in NMP to form a susceptorcomposition. The composition was coated on a PP non-woven web and wasallowed to air dry. The slightly tacky web was placed between polyolefinsubstrates and the assemblies were RF heated in the RF work station at14.65 MHz and about 0.8 kW for 5 seconds.

[0441] Good adhesion was obtained in each case.

Example 3b

[0442] A susceptor composition capable of inductive activation wasprepared with an aqueous dispersion of a sulfopolyester, EASTEK 1300Polymer (available from Eastman Chemical Company), by addition of SnCl₂.A precipitate was recovered from this mixture and a film from thisprecipitate was obtained by pressing between hot platens at about 200°F. and 1000 psi for a short time. This film was slightly wet and wassandwiched between a PE film and a PP non-woven web. The assembly was RFheated in the RF work station at 14,63 MHz and about 0.8 kW for 1second. Good adhesion without substrate deformation was achieved.

Example 3c

[0443] Analogous to Example 3b, additional experiments were performed inwhich slightly wet-to-touch thin films of the susceptor compositions ofexample 3b were sandwiched between two stacks consisting of multiplelayers of non-woven PP or multiple layers of non-woven PP laminated toPE film. Three different types of sandwiched assemblies were tested,including: (1)8 layers of non-woven PP/susceptor composition/8 layers ofnon-woven PP, (2) 2 layers of PP non-woven laminated to PEfilm/susceptor composition/2 layers of PP non-woven laminated to PE film(with PP non-woven facing PE film at the stack interface), and (3) 4layers of PP non-woven/susceptor composition/4 layers of PP non-woven.In each case, the assemblies were RF heated in the RF work station at14.63 MHz and about 0.8 kW for 1 second. In all cases, good adhesionoccurred between the multilayer stacks without causing distortion to thestacks.

[0444] In this experiment, each multilayered stack was pre-assembledusing a conventional contact adhesive, and the two stacks were lateradhered to one another using the susceptor composition. However, it iscontemplated in the practice of the invention that each multilayer stackcan be preassembled using a susceptor composition to eithersimultaneously or sequentially bond or adhere the various layers of eachstack.

Example 4

[0445] Based on the success of the susceptor compositions tested inExamples 1--3b, other susceptor compositions were made and tested. Inthis example, sample compositions (in constituent concentrationsconsistent with the parameters described above) were tested inhalf-filled test tubes nearly centered within the coil of the RFequipment described in FIG. 40. Various settings for voltage input andfrequency of the current were investigated. Table 3 summarizes theresults of these experiments. The effectiveness of RF heating is shownby the time required for the samples to boil or to rise to the indicatedtemperature. TABLE 3 Selected Test Tube Experiments with PotentialSusceptors Frequency, Input, Field, Time to boil or Materials MHz mV Vtemperature rise Solid Salts SnCl₂ × 2H₂O 13.73 300 7.8 Poor heatingSnCl₂ × 2H₂O 13.73 600 15 39 sec., 122° F. SnCl₂ 13.74 800 ˜20 Poorheating LiClO₄ × 3H₂O 13.74 800 ˜20 10 sec. Aqueous Solutions DistilledWater 13.75 800 80 sec., 117° F. LiClO₄ 13.73 800 ˜20  3 sec. SnCl₂ 800˜20  5 sec. NaCl 13.67 800 ˜2.2  3 sec. NaCl 5.833 320 ˜2.2 20 sec. NaCl3.719 10 58 30 sec. Li-acetate 13.73 1000 10 sec. Nonaqueous SolutionsNMP 13.74 800 60 sec., 89° F.  NMP/SnCl₂ 13.74 800 47 sec., 350° F.NMP/PVP/SnCl₂ 13.73 685 20  8 sec., 142° F. NMP/PVP/LiClO₄ × 13.73 64320  6 sec., 135° F. 3H₂O NMP/PVP/Li-acetate × 13.73 600 18 18 sec. 2H₂OLiquid Samples Uni-REZ 2115 13.75 1000 75 sec., 126° F. MICHEM 498313.77 10 40 30 sec., 178° F. MICHEM ACRYLIC 1 13.73 800  4 sec.

[0446] These tests show that, as expected, aqueous solutions of varioussusceptors, such as salts, coupled very well with the RF energy. Alltested susceptor compositions came to a boil within 3-30 seconds. Asdiscussed above, SnCl₂ dissolved in NMP also coupled very effectively.Although a boiling time of 47 seconds is shown in this experiment, thetemperature of 350° F. reached by this mixture is substantially higherthan is required for heat bonding polyolefins.

[0447] In the section on nonaqueous solutions in Table 3, it can be seenthat while NMP is only a weak susceptor in its own right, it couplesvery effectively with the RF energy, when a variety of salts aredissolved in it. It was also observed that the solution's ability tosolubilize salts seems to be enhanced when PVP is dissolved in it. Sincethe compositions shown in Table 3 were not optimized, the RF heatingcapability of the solutions appear to be very good.

[0448] The last section of Table 3 shows the RF heating capability ofsome liquid polymers. They range from very mild coupling ability to verypowerful coupling ability in the case of MICHEM ACRYLIC 1 (availablefrom Michelman Corporation), a styrenated ethylene-acrylic acid polymer.

Example 5

[0449] This experiment tested the compatibility of various film formingand adhesive polymers with modifying resins and additives and withinorganic or organic susceptors (in constituent concentrationsconsistent with the parameters described above). A series of experimentswere conducted with low-density polyethylene (LDPE) as the substrate, assummarized in Table 4. TABLE 4 Bonding Feasibility Experiments With aLow Density Polyethylene Substrate Frequency, Input, Sample Mhz mV TimeAdhesion Substrate ELVAX 40W + UNI-REZ 14.55 500 1 min. None LDPE 2641ELVAX 40W + UNI-REZ The Li-acetate did not mix with the polymers under2641 + Li-acetate pressing conditions ELVAX 40W + N,N- 14.54 500 1 min.None LDPE ethylenebis-stearamide @80/20 ELVAX 40W + N,N- 14.54 650 1min. Slight LDPE EbSA @80/20 + MICHEM ACRYLIC 1 MICHEM ACRYLIC 1 14.54650 30 sec. Slight LDPE PRIMACOR 3460 + The Li-acetate did not mix withthe polymers under Li-acetate pressing conditions N,N-EbSA + ELVAX 14.6850 30 sec. Partial LDPE 40W + Poly (ethylene- maleic anhydride) + Li-acetate + MICHEM PRIME 4983 ELVAX 40W + Li-acetate + 14.6 850 30 sec.Partial LDPE MICHEM PRIME 4983 ELVAX 40W + 14.6 850 15 sec. Partial,LDPE MICHEM PRIME 4983 good UNI-REZ 2641 14.6 850 30 sec. Partial, LDPEgood ELVAX 40W + 14.6 850 30 sec. Partial, LDPE UNI-REZ 2641 + goodMICHEM PRIME 4983 Polyethylene (AS) + 14.6 850 15 sec. Partial, LDPEAlliedSignal GRADE A-C + good MICHEM PRIME 4983 Polyethylene (AS) + 14.6850 30 sec. Partial, LDPE MICHEM PRIME 4990 good ELVAX 40W + Fe₂O₃ 14.6850 30 sec. None LDPE ELVAX 40W + 14.6 850 15 sec. Good LDPE MICHEMPRIME 4990 ELVAX 410 + N,N-EbSA + 14.6 850 30 sec. None LDPE PEMA ELVAX410 + N,N-EbSA + 14.6 850 30 sec. None LDPE PEMA + KEN-REACT LICA 44ELVAX 410 + N,N-EbSA + 14.6 850 10 sec. Partial, LDPE PEMA + MICHEM goodACRYLIC 1 ELVAX 40W + Li- 14.6 850 15 sec. Good LDPE acetate/MICHEMACRYLIC 1 (paste) ELVAX 40W + 14.6 850 15 sec. Good LDPE MICHEM ACRYLIC1 ELVALOY EP 4043 14.6 850 30 sec. None LDPE MICHEM ACRYLIC 1 ELVAX 40W + UNI-REZ 14.6 850 30 sec. None LDPE 2641 + STEROTEX HM wax + MICHEMACRYLIC 1 SnCl₂ + NMP + PVP 14.54 850 10 sec. None Mylar/dry K29-30 +0.1% 14.54 850 30 sec. None Mylar/dry SURFYNOL 104PA

[0450] Several susceptors which had been very effective in test tuberuns did not always lead to good bonding or adhesion in these trials.MICHEM ACRYLIC 1 is a good example. Likely reasons include: (a) thesusceptors were only effective wet and lost their coupling ability whenused in a dry film, or (b) the susceptor itself was not a good adhesiveand formed a barrier to melted PE bonding to itself. There was anindication that the second reason prevailed when it was shown that thesusceptors performed better when blended with PE or EVA which could actas hot melt adhesives for the substrates. Better results were obtainedwith MICHEM PRIME 4983 and 4990, MICHEM ACRYLIC 1, and UNI-REZ 2641 incombination with either PE or EVA. However, N,N-ethylene-bisstearamide,which was described in the Degrand reference, was not very effective inthese experiments. A number of trials provided partial adhesion, asnoted in Table 4, which were likely caused by the inability of the filmholder to clamp the substrates tightly and flat. Although the shortestsuccessful heating times were on the order of 10 to 15 seconds, whichwould be too long for a commercial operation, the results are positive,in that both the adhesive compositions and the operation of the filmstation can be further optimized without undue experimentation.

Example 6

[0451] Another series of experiments were performed with otherpolyolefin substrates, including a PP non-woven. These trials aresummarized below in Table 5. Very good bonds were obtained with severalcompositions at dwell times down to about 1 second. While this may betoo long for some commercial applications, it is highly encouraging fortrials that were not optimized with regard to either the susceptorcomposition or the test equipment. TABLE 5 Bonding Experiments WithPolyolefin Substrates Frequency, Input, Sample Mhz mV Time AdhesionSubstrate ELVAX 40W 14.61 850 30 sec. None PP nonwoven (Du Pont 40%vinyl acetate to polyethylene) ELVAX 40W + 14.61 850 15 sec. Good PPnonwoven MICHEM PRIME 4990 ELVAX 40W + UNI- 14.61 850 30 sec. None PPnonwoven REZ 2641 + STEROTEX HM wax + MICHEM ACRYLIC 1 ELVAX 40W + UNI-14.61 850 15 sec. Good PP nonwoven REZ 2641 + MICHEM ACRYLIC 1 SnCl₂ +NMP + PVP 14.61 850  1 sec. Good PP nonwoven K29-30 + 0.1% SURFYNOL104PA(Dried 90 min) 14.61 850  5 sec. Good PP nonwoven (Dried 15 hrs) 14.61850 25 sec. None PP nonwoven (Dried 15 hrs + NMP) 14.61 850  2 sec. GoodPP nonwoven SnCl₂ + NMP + PVP 14.61 850  1 sec. None PE/PE K29-30 + 0.1%SURFYNOL 104PA SnCl₂ + NMP + PVP 14.61 850  1 sec. Slight PP/PP n/wK29-30 + 0.1% 14.61 850  2 sec. Good PP/PP n/w SURFYNOL 104PA ELVAX40W + 14.61 850 30 sec. None PP nonwoven UNI-REZ 2641 + Indium tin oxideSURFADONE LP-300 + 14.61 850 30 sec. None PP nonwoven SnCl₂ PVP/VAS-630 + SnCl₂ + 14.61 850  1 sec. Good PP nonwoven NMP 14.61 850  1 sec.Slight PE/PE PVP/VA S-630 + SnCl₂ + 14.61 850  1 sec. Good PP nonwovenNMP + Fumed silica 14.61 850  5 sec. Slight PE/PE 14.61 850  2 sec.Slight PP/PP n/w ELVAX 40W + 14.61 850 30 sec. None PP nonwoven UNI-REZ2641 + Li-acetate, pressed Li-acetate × 2H₂O 14.61 850 30 sec. None Nomelting Mg(NO₃)₂ × 6H₂O 14.61 850 30 sec. None No melting MgAc × 4H₂O14.61 850 30 sec. None No melting Stearic acid + 14.61 850  2 sec. NonePP nonwoven Cetyl alcohol + 14.61 850 10 sec. Good PP nonwoven Mg(NO₃)₂× 6H₂O EVA AC-400 + 14.61 850 2, 5 and None PP nonwoven SURFADONELP-300 + 10 sec. SnCl₂

[0452] Some of the better results were obtained with compositionscontaining PVP or PVP/VA and SnCl₂ salt dissolved in NMP (in constituentconcentrations consistent with those discussed above). It was shown,however, that thorough drying of the susceptor composition eliminatedits ability to couple with the RF field. It appears that the mobility,provided by the presence of at least a small amount of NMP solvent, isimportant for efficient coupling to the applied RF field. This mobilityfunction can be provided by the selection of an appropriate nonvolatileplasticizer, such as epoxidized oils, polyhydric alcohols, substitutedamides, sulfonamides, aryl and alkyl aryl phosphates, polyesters and awide variety of esters, including benzoates, phthalates, adipates,azelates, citrates, 2-ethylbutyrates and hexoates, glycerides,glycollates, myristates, palmitates, succinates, stearates, etc.Plasticizers are used to solvate a material, and thus improve itsmolecular mobility if it has become too rigid.

[0453] In general, ethylene co-polymers with functionality providing (a)enhanced compatibility and (b) ionic or highly polar constituents areeffective in bonding or adhering substrates, together with salts thatare either soluble or readily dispersed in the polymer matrix. There isalso evidence that in some compositions mobility of the dipoles must beassured. This was achieved in the presence of such high-boiling solventsas NMP. It can also be extrapolated that other high boiling solvents ornon-volatile plasticizers can achieve the same effects with morereproducible results.

[0454] These example susceptor compositions utilize a combination ofpolar components and hydrated salts in a polymer matrix plasticized withhigh boiling and high dielectric constant additives that are activatableat a relatively low frequency of about 15 MHz.

[0455] The methods and experiments set forth above will allow those ofskill in the art to determine without undue experimentation that aparticular mixture would be suitable for bonding or adhering substratesaccording to the present invention.

Example 7

[0456] This example demonstrates RF-heatable thermoplastic compositionsderived from the combination of various ion-containing polymers withglycerin. These compositions are shown to be significantly moresusceptible to RF heating than either the component ion-containingpolymers or glycerin are by themselves.

Example 7a

[0457] Several compositions comprising 70 wt % sulfonated polyesters in30 wt % glycerin were prepared. Each sample was prepared by first mixing14 grams of sulfopolyester material with 6 grams of glycerin in a 60milliliter glass jar. The open topped jar was heated in a convectionoven at 165 C for 1 hour. After thirty minutes, the composition wasremoved from the oven and hand stirred for I minute and then immediatelyreturned to the oven. After an additional 30 minutes of heating at 165C, the composition was removed from the oven and hand stirred for 1minute. While the composition was still molten, it was hand-drawn into a1 inch wide by 3 inch long by 0.006 inch thick coating on the surface ofa 0.004 inch thick sheet of transparency film (PP2500 series 3Mtransparency film) that was supported on a 180° F. 10 inch×10 inchCorning model PC620 hot plate. Immediately after the composition wascoated to the film, the coated film was removed from the hot plate andallowed to cool to room temperature. The samples were then evaluated forfilm properties and RF heating.

[0458] The RF equipment setup used for testing this example and examples8-16 consisted of the RF probes described in FIG. 42 and the RFequipment described in FIG. 41. Unless otherwise noted, in each case a1-inch×3-inch sample (410) was placed over the RF probes as shown inFIG. 41. The distance from the surface of the probes to the sample wasabout 0.016 inches. The sample was heated at about 1 KW input power intothe tuned heat station 4122 (or impedance matching circuit 4122) atabout 13.5 MHz for the time required to cause observable heating andmelting in the activation region of the RF probes. TABLE 6 Film Time toMelt Experiment # Composition Description Properties (s) BRANCHEDSULFONATED POLYESTERS . . . (Eastman A Polyesters, Available fromEastman Chemical Company, Kingsport, TN, USA) 1 70 wt % AQ1045 Clear,tacky, 0.25 30 wt % glycerin flexible. 2 70 wt % AQ1350 Clear, tacky,0.25 30 wt % glycerin flexible. 3 70 wt % AQ1950 Clear, tacky, 0.25 30wt % glycerin flexible. 4 70 wt % AQ14000 Clear, tack, 0.25 30 wt %glycerin flexible. LINEAR SULFONATED POLYESTERS . . . (Eastman APolyesters, Available from Eastman Chemical Company, Kingsport, TN, USA)5 70 wt % AQ35S White, tack- 0.5 30 wt % glycerin free, flexible. 6 70wt % AQ38S White, tack- 0.5 30 wt % glycerin free, flexible. 7 70 wt %AQ55S Clear, tack- 0.2 30 wt % glycerin free, flexible.

Example 7b

[0459] Several compositions comprising 70 wt % ethylene acrylic acidcopolymers in 30 wt % glycerin were prepared. Each sample was preparedby first mixing 52 grams of ethylene acrylic acid copolymer material (a25 wt % solids emulsion) with 5.57 grams of glycerin in a 60 milliliterglass jar. The combined materials were then mixed for 10 minutes toresult in an emulsion. The resulting emulsion was then cast onto a sheetof 0.004 inch thick transparency film (PP2500 series 3M transparencyfilm) at room temperature. The cast emulsion was then allowed todry-down under a heat lamp to form a film. The samples were thenevaluated for film properties and RF heating. TABLE 7 Time to Experi-Melt ment # Composition Description Film Properties (s) ETHYLENE ACRYLICACID COPOLYMERS (Acid Form) . . . (MICHEM 4983P, Available fromMichelman Incorporated, Cincinnati, OH, USA) 1 100 wt % MICHEM 4983PClear, colorless, 28 brittle, tack-free. 2 70 wt % MICHEM 4983P Clear,colorless, less  0.5 30 wt % glycerin brittle, tack-free. 3 50 wt %MICHEM 4983P Clear, colorless,  0.4 50 wt % glycerin flexible,tack-free. ETHYLENE ACRYLIC ACID COPOLYMERS (Sodium Salt Form) . . .(MICHEM 48525P, Available from Michelman Incorporated, Cincinnati, OH,USA) 4 100 wt % MICHEM Clear, colorless, No Heating 48525P brittle,tack-free. in 1 minute. 5 70 wt % MICHEM 48525P Clear, colorless,  0.530 wt % glycerin flexible, tack-free, rubbery. 6 50 wt % MICHEM 48525PClear, colorless, 0.2-0.4 50 wt % glycerin flexible, tack-free, rubbery.

Example 7c

[0460] Several compositions comprising 70 wt % vinyl acetate acryliccopolymers in 30 wt % glycerin were prepared. Each sample was preparedby first mixing 46.67 grams of vinyl acetate acrylic copolymer material(a. 55 wt % solids emulsion) with 3 grams of glycerin in a 60 milliliterglass jar. The combined materials were then mixed for 10 minutes toresult in an emulsion. The resulting emulsion was then cast onto a sheetof 0.004 inch thick transparency film (PP2500 series 3M transparencyfilm) at room temperature. The cast emulsion was then allowed todry-down under a heat lamp to form a film. The samples were thenevaluated for film properties and RF heating. TABLE 8 VINYL ACETATEACRYLIC COPOLYMERS . . . (ROVACE HP3442, Available from Rohm and Haas,Philadelphia, PA, USA) Composition Time to Melt Experiment # DescriptionFilm properties (s) 1 100 wt % HP3442 Clear, colorless, No Meltingflexible, tack-free. in 1 minute 2  90 wt % HP3442 Clear, colorless, 0.3 10 wt % glycerin flexible, very tacky, with good cohesion.

Example 7d

[0461] This example demonstrates how the addition of glycerin as well asadjustments in pH to gelatin solutions can affect the properties ofderived gels.

[0462] Several compositions were prepared as solutions of a commerciallyavailable gelatin (Eastman 45Y56-853-3V0-6CS available from EastmanGelatine Corporation). All compositions had water. Some solutions hadglycerin added to them. Some solutions had their pH adjusted by theaddition of ION NaOH or 6N HCl. The compositions were prepared asfollows:

[0463] Composition #1 was prepared by adding 70 grams of gelatin to 280grams of water and stirring and heating the resulting mixture at about65° C. for 1 hour to obtain a solution. The solution had a pH of 6.18 at65° C.

[0464] Composition #2 was prepared by stirring 6 grams of glycerin into70 grams of composition #1. The solution had a pH of 5.8 at 65° C.

[0465] Composition #3 was prepared by stirring drops of ION NaOH (about25 drops) into 125 mls of composition #1, until the resulting solutionhad a pH of 10.1 at 65° C.

[0466] Composition #4 was prepared by stirring 8.51 grams of glycerininto 99.3 grams of composition #3 to result in a solution with a pH of10.1 at 65° C.

[0467] Composition #5 was prepared by stirring drops of 6N hydrochloricacid (about 90 drops) into 125 grams of composition #1, until theresulting solution had a pH of 1.9 at 65° C.

[0468] Composition #6 was prepared by stirring 5.361 grams of glycerininto 62.57.grams of composition #5 to result in a solution with a pH of1.9 at 65° C.

[0469] Each gelatin solution was cast onto a sheet of transparency film(3M PP2500 Transparency Film) and allowed to set-up at room temperatureto form a gel film. The gels differed in their film properties and intheir RF-heating properties as described in Table 9.

[0470] Gelatin films (susceptors) may not act as a good adhesive on lowenergy surfaces, such as PE, PP, etc. However, the are expected toperform effectively as adhesives on polar substrates, such as paper,Kraft paper, linear boards, wood, etc. TABLE 9 GELATINS . . . (Eastman45Y56-853-3V0-6CS gelatin, Available from Eastman Gelatin, USA)Composition Time to Melt Experiment # Description Film properties (s) 1gelatin Brittle w/ No Heating pH 5.8 at 65° C. poor adhesion to insubstrate. 1 minute. 2 70 wt % gelatin Flexible w/ 10 30 wt % glyceringood adhesion to pH 5.8 at 65° C. substrate. 3 gelatin Brittle w/ NoHeating pH 10.1 at 65° C. poor adhesion to in substrate. 1 minute. 4 70wt % gelatin flexible w/ 4 30 wt % glycerin good adhesion to pH 10.1 at65° C. substrate. 5 gelatin Brittle with poor 17 pH 1.9 at 65° C.adhesion to substrate. 6 70 wt % gelatin Flexible w/good <1 30 wt %glycerin attachment to pH 1.9 at 65° C. substrate.

Example 8

[0471] Several compositions were prepared by mixing various polarmaterials with a representative ionomer (Eastman AQ35S Sulfopolyester).In each case, the compositions are demonstrated to be more susceptibleto RF heating than the component ionomer or polar material bythemselves.

[0472] Each composition is comprised of 70 wt % AQ35S in 30 wt % polarmaterial. Each sample was prepared by first mixing 46.67 grams of AQ35D(a 30 wt % solids emulsion) with 6 grams of polar carrier in a 60milliliter glass jar. The combined materials were then mixed for 10minutes to result in an emulsion. The resulting emulsion was then castonto a-sheet of 0.004 inch thick transparency film (PP2500 series 3Mtransparency film) at room temperature. The cast emulsion was thenallowed to dry-down under a heat lamp to form a film. The samples werethen evaluated for film properties and RF heating. TABLE 10 VARIOUSPOLAR MATERIALS USED IN COMPOSITIONS COMPRISING: 70 wt % EASTMANAQ35S/30 wt % POLAR MATERIAL. Experi- Time to ment Film Melt #Composition Description properties (s) 1 70 wt % EASTMAN AQ35S Clear,tack- 1 30 wt % Ethylene Glycol free, flexible. (The DOW ChemicalCompany, Midland, MI, USA) 2 70 wt % EASTMAN AQ35S White, slightly 0.15030 wt % 1,2-propylene glycol tacky, flexible. (The DOW Chemical Company,Midland, MI, USA) 3 70 wt % EASTMAN AQ35S Clear, yellow, 0.4 30 wt %polyethylene glycol 200 tacky, flexible. (Union Carbide Chemicals andPlastics Company Inc., Danbury, CT, USA) 4 70 wt % EASTMAN AQ35S Cloudy,12 30 wt % polyethylene glycol 8000 orange, tack- (Union CarbideChemicals and free, w/ some Plastics Company Inc., undissolved Danbury,CT, USA) polyethylene glycol, flexible. 5 70 wt % EASTMAN AQ35S White,tack- 1.5 30 wt % hexylene glycol free, flexible. (Shell ChemicalCompany, Houston, TX, USA) 6 70 wt % EASTMAN AQ35S Clear, slightly .2530 wt % diethylene glycol tacky, flexible. (The DOW Chemical Company,Midland, MI, USA) 7 70 wt % EASTMAN AQ35S Clear, tack- <0.5 30 wt %glycerin free, flexible. (The Procter and Gamble Company, Cincinnati,USA) 8 70 wt % EASTMAN AQ35S Slightly 2 30 wt % sorbitol cloudy, (Sigma,St. Louis, MO, USA) slightly tacky, flexible. 9 70 wt % EASTMAN AQ35SClear, yellow, 10 30 wt % NPC-ST-30, Colloidal silica slightly tacky, inethylene glycol monopropyl flexible. ether. (Nissan Chemical Company,Japan; New York Office, Tarrytown, NY, USA) 10 70 wt % EASTMAN AQ35SSlightly 0.2 30 wt % EG-ST, Colloidal silica in cloudy, ethylene glycol.slightly tacky, (Nissan Chemical Company, flexible. Japan; New YorkOffice, Tarrytown, NY, USA) 11 100 wt % EASTMAN AQ35S Clear, tack- NO NOADDED POLAR MATERIALS free, flexible. HEAT (CONTROL) in 1 minute. 12 70wt % EASTMAN AQ35S Clear, tack- 2.8 30 wt % N-methylpyrrolidone free,flexible. (Aldrich Chemical Co., Inc. Milwauke, WI) 13 70 wt % EASTMANAQ35S Clear, tack- 0.3 30 wt % dimethyl formamide free, flexible.(Aldrich Chemical Co., Inc. Milwauke, WI) 14 70 wt % EASTMAN AQ35SClear, slightly 0.2 30 wt % formamide tacky, flexible. (Aldrich ChemicalCo., Inc. Milwauke, WI) 15 70 wt % EASTMAN AQ35S Clear, slightly 0.15 30wt % dimethyl sulfoxide tacky, flexible. (Aldrich Chemical Co., Inc.Milwauke, WI)

Example 9

[0473] Thermoset polymers are a class of polymeric systems formed bychemical (usually covalent bonding) reaction of lower molecular weightfunctional building blocks. For instance, epoxy thermoset polymers areformed by the reaction of oxirane groups of epoxy compounds with otherfunctional groups such as hydroxyl, carboxyl, amine etc. In the case ofurethanes, isocyanate groups are reacted with functional groups such asamines, hydroxyls etc. Chemical reactions of the functional groups ofthe building blocks typically need energy source such as heat, radiationand presence of catalyst. The reaction product resulting from such aninteraction leads to crosslinking between the functional groups of thebuilding blocks which in turn gives a cured polymeric system with manydesirable properties such as improved heat, chemical and solventresistance, enhanced strength and mechanical properties etc. A keyfeature of thermoset systems is the fact that once the crosslinks areformed in the cured state it is very difficult to reverse it.

[0474] A convenient way to study the crosslinking reaction in athermoset system is to follow the gelling reaction. At the start of thecrosslinking reaction, viscosity of the initial reaction mixture is low.In the presence of appropriate catalyst and energy source, chemicalcrosslinking starts to take place with increase in molecular weight andviscosity. After a critical stage of the crosslinking reaction has takenplace, the system sets up to an insoluble (in a solvent such as MEK inwhich the starting compounds are soluble) gel. Physico-chemically,chemical bonds are being formed leading to a network structure of thecured system. It has been shown that many of the properties of athermoset system (such as glass transition temperature, solvent andchemical resistance, mechanical properties etc) can be readilycorrelated to the gel content of the system.

[0475] The degree of cross linking of various thermoset systems wasassessed by measuring the gel content of formulation after exposure toRF field to different time and energy levels. Increase in gel content ofa given composition after RF exposure (compared to the gel content ofthe same composition after air drying for several hours) is taken as ameasure of cure of the thermoset system.

[0476] Typical gel measurements were carried out as follows.

[0477] A sample of the formulation is applied to a glass slide. Thesample is air dried for a 1-2 hours so the applied layer is dry totouch. Sample weight is noted as “A” after taking into account the tareweight of glass slide. Then it is exposed to RF source (in the case ofcontrol experiments, the sample is put in a conventional laboratory ovenat a set temperature and time). The cured sample is cooled down toambient temperature. The glass slide containing the cured sample isdipped in 40 ml of MEK for 10 minutes. The slide is taken out andair-dried prior to weighing. Sample weight is noted as B.

% Gel content is calculated as (B/A)×100

[0478] It is worth noting that gel content as measured by the aboveprocedure gives only the initial cure state of the thermoset system.Typically, crosslinking reaction progress further upon aging leading toa higher cured state of thermoset system.

[0479] In the following experiments, the following materials were used:

[0480] EPON 828: Diglycidylether of bisphenol-A from Shell Chemicals.

[0481] ANCAMINE 2441 catalyst, a modified polyamine from Air Products &Chemicals Inc. nEpiRez dispersion, a bisphenol A based epoxy dispersionfrom Shell Chemicals.

[0482] Epicure 8536-MY60, an amine curing agent from Shell Chemicals.

[0483] MAINCOTE HYDUR, a self-reactive acrylic emulsion from Rohm &Haas.

[0484] Aropol 7241, an isophthalic polyester (unpromoted) from AshlandChemical.

[0485] KELSOL 5293, a water dispersible polyester from Reichhold.

[0486] CYMEL 385, butylated urea formaldehyde resin from CytecIndustries.

[0487] DESMODUR-W, an aliphatic diisocyanate {CAS #5142-30-1,(4-isocyanatocyclohexyl) methane}from Bayer

[0488] FORMREZ 11-36, a polyester diol from Witco

[0489] T-12 catalyst, dibutyltindilaurate from Air Products & Chemicalsinc.

[0490] Eastman A 35 D. sulfonated branched polyester from EastmanChemicals.

[0491] A. Epoxy Resins:

[0492] Epoxy resins are typically cured to a thermoset state byapplication of heat in the presence of catalysts such as amines, acids,anhydrides etc. By proper selection of epoxy resin, catalyst (amine,acid etc.) and optionally a polar carrier such as water, glycerin andsimilar high dielectric constant liquids, it is possible to formulate RFcured thermoset epoxy systems of potential interest in diverseapplications, such as: adhesives and coatings for conventional and sprayapplications on plastics, metals, wood, etc; corrosion resistantcoatings; industrial and protective coatings; top coats; automotivecoatings; lamination of composites; laminating adhesives; bonding ofstructural composites; inks and decorative coatings; barrier coatings;etc.

[0493] The effect of time and temperature on some thermally cured epoxyresin systems using typical cure conditions is shown in this example.The composition included: EPON 828 resin   3 parts ANCAMINE 2441catalyst 0.3 parts

[0494] The above composition was air dried without any heat and the gelcontent measured. It was found to be zero showing that the resin is notcross-linked to a cured system.

[0495] The above composition was heated to 130 deg C for 5 minutes andthe gel content of the sample was found to be 11%. This shows that thereis some crosslinking occurring under this condition.

[0496] The above composition was heated to 130 deg C for 15 minutes andthe gel content was found to be 48%. As expected, longer exposure tohigher temperature increases crosslink density and gel content.

[0497] The above composition was heated to 120 deg C for 20 minutes andthe gel content was found to be 42.5%. This shows that longer exposuretime at a lower temperature compared to previous experiment did notincrease gel content. From this observation, one can conclude thattemperature has a more significant influence on crosslink density andgel content of the system.

[0498] The above composition was exposed to 120 deg C for 30 minutes andthe gel content was found to be 73.5%.

[0499] The main conclusion from the above experiments is that a fairlylong time (order 30 minutes) is needed to reach a high gel contentthermoset epoxy resin system, cured by conventional thermal energy.

[0500] In the next series of experiments, similar epoxy compositionswere evaluated when exposed to RF (14.7 MHz) for various lengths of timeand energy. The composition included: EPON 828 2.1 Parts ANCAMINE 24410.5 parts

[0501] The above composition was air-dried and the gel content of thedried sample was found to be 10.7%. This shows that there is a verysmall level of gel in the air-dried (1 hour) sample.

[0502] 10% Glycerin was added to the above composition and the sampleair-dried for 1 hour and its gel content was found to be 4.3%. This datashows that glycerin tends to solubilize the gel under air dry condition.

[0503] The above composition (without glycerin) was applied onto a glassslide and was exposed to 500 mv for 2.5 minutes and its gel content wasfound to be 8.5%. This shows that there is not much activation underthis level of RF energy.

[0504] The 10% glycerin composition was applied to a glass slide and thesample was exposed to 500 mV for 2.5 minutes. Gel content of the samplewas found to be 77.3%. This result shows that addition of glycerinenhances the RF susceptibility of the resin and high level ofcrosslinking is achieved.

[0505] These experiments clearly show that epoxy resins can be activatedin a very short period of time (compared to thermal curing conditions),especially in the presence of a polar carrier such as glycerin.

[0506] In the next series of experiments, another type of epoxy andcuring agent was tested. The composition included: EPI-REZ 3520-WY-55 2parts Epicure 8536-MY60 1 parts

[0507] The above composition was applied to a glass slide and activatedunder 100 mV for 5 minutes. No heat was noted and the gel content wasfound to be 19.3%

[0508] The same composition was activated under 500 mV for 5 minutes.Gel content was found to be 52.5%. This shows that higher power comparedto first experiment is needed for crosslinking to take pace.

[0509] 10% Glycerin was added to the above composition and the sample,after drying on a glass slide, was activated for 5 minutes under 500 mV.The gel content was found to be 52.4%, which is very similar to what wasobtained without any glycerin. This result shows that the presence ofglycerin or other carrier is not necessary for RF activation in allcases, especially if the resin system is water based such as the Epi Rezresin.

[0510] B. Acrylic System:

[0511] In this series of experiments, the use of RF activation for anacrylic class of resin is demonstrated.

[0512] MAINCOTE HYDUR 30, a water based acrylic emulsion with carboxyland unsaturation functionalties from Rohm and Haas was tested. Thesample was air-dried and its gel content was found to be 37%. Thisresult shows that the unsaturation in the acrylic resin results in somecrosslinking due to air oxidation, as seen in drying oils and alkydresins.

[0513] 10% glycerin was added to MAINCOTE HYDUR 30 and the gel contentof the air dried sample was found to be 4.6%. This result shows thatglycerin acts as good solvent for the air-dried sample.

[0514] MAINCOTE HYDUR 30 was applied to a glass slide and the sampleexposed to 500 mV for 2.5 minutes. The gel content was found to be61.5%. This clearly shows that RF field activates the acrylic resinleading to high levels of crosslinking.

[0515] 10% Glycerin/MAINCOTE HYDUR 30 was exposed to 500 mV for 2.5minutes. The gel content was found to be 92.3%. This result shows thatpresence of glycerin promotes RF coupling with the resin.

[0516] MAINCOTE HYDUR 30 was exposed to 700 mV for 2.5 minutes and thegel content was found to be 81.8%. This shows that increased RF powerpromotes crosslinking of acrylic resin.

[0517] 10% Glycerin/MAINCOTE HYDUR 30 was exposed to 700 mV for 2.5minutes and the gel content of the sample was found to be 100%. Thisresult shows the beneficial role of glycerin in promoting RF activationof acrylic resin.

[0518] The next experiment is a comparative example showing thermalcuring of acrylic resin. MAINCOTE HYDUR was heated to 100 deg C for 5minutes and the gel content was found to be 93%. Note that gel contentof RF activated sample is higher even though it was exposed only forhalf the duration to energy.

[0519] This series of examples show that functionalized acrylic polymerscan be activated under RF energy.

[0520] C. Polyester Resin

[0521] In this series of experiments, the RF response of polyester/vinylester resins was studied.

[0522] Aropol 7241, an isophthalic polyester resin from AshlandChemical, was applied to a glass slide and the dried sample was exposedto RF field at 500 mV and 5 minutes. The gel content was found to be51.3%.

[0523] This result shows that RF energy can activate an isophthalicpolyester resin.

[0524] KELSOL 5293, a polyester dispersion from Reichhold Chemicals, wastested in this example. The composition included: KELSOL 5293   2 partsCYMEL 385 crosslinker 0.6 parts

[0525] The composition was exposed to RF for 2.5 minutes at 500 mV. Thegel content was found to be 8.5%.

[0526] 10% glycerin was added to the composition and exposed to RF for2.5 minutes at 500 mV. The gel content was found to be 21.9%. This showsthat addition of glycerin promotes RF activation.

[0527] The above composition (without glycerin) was exposed to 700 mVfor 2.5 minutes and the gel content was found to be 73.7%. This resultshows that exposure to higher RF field leads to higher gel content.

[0528] The composition comprising 10% glycerin was exposed to 700 mV for2.5 minutes and the gel content was found to be 59.5%.

[0529] These experiments show that RF energy can be used to activatepolyester type resins.

[0530] D. Urethanes

[0531] A linear polyurethane composition based on DESMODUR-W (analiphatic diisocyanate from Bayer) and FORMREZ 11-36 (a polyester diolfrom Witco) was evaluated. The composition included: DESMODUR W 0.75parts Formerez 11-36  3.2 parts T-12 catalyst from Air Products &Chemicals 1-2 drops

[0532] A glass slide containing the above composition was exposed to 700mV RF field for 5 minutes and the gel content was measured to be 11.4%.(Note: At 500 mV, the gel content was zero for 2.5 and 5 minuteexposures without glycerin and 1.3% and 8.3% for 2.5 and 5 minuteexposures with 10% glycerin).

[0533] 10% Glycerin was added to the above composition and the RFactivation repeated under the same conditions (700 mV and 5 minutes).The gel content was found to be 27%. This level of gel content is quitegood for a linear polyurethane.

[0534] This result shows that addition of glycerin promotes urethanereaction and gel formation. It is very likely that hydroxyl groupspresent in the glycerin molecule is acting as reactive polyol in theformation of urethane. It may be possible to increase the gel content byincreasing the ratio of isocyanate in the formulation relative topolyol. It may also be possible to increase the gel content of thecomposition by partially replacing the diisocyanate (DESMODUR W) andpolyester diol (Formerez 11-36) with multifunctional isocyanate such aspolymeric MDI (methylene bisdiphenyldisocyanate) and triols. Use ofmultifunctional isocyanate and polyol should significantly increase gelcontent close to 100%. Use of isocyanate terminated prepolymer of highermolecular weight (8,000-10,000) in the urethane reaction may alsoincrease gel content of the system.

Example 10 Effect of “Susceptor” Addition on RF Activation of Acrylicand Polyesters

[0535] The effect of adding 4-styrene sulfonic acid, Na salt, vinylsulfonic acid, Na salt and A 35 D sulfonated polyester from EastmanChemicals on RF activation of acrylic and polyester resins wasevaluated. A first composition included: MAINCOTE HYDUR- 95 parts4-styrene sulfonic acid, Na salt  5 parts

[0536] The above composition was evaluated as described in previousexamples at 700 mV and 2.5 minutes. The gel content was found to be45.5%. Gel content of the sample without 4-styrene sulfonic acid, Nasalt, under the same conditions was found to be 81.8% (see above).

[0537] 10% Glycerin was added to the above composition and the sampleevaluated under 700 mV and 2.5 minutes exposure conditions. The gelcontent was found to be 66.7%. Gel content of the sample withoutsusceptor was 100% (see above).

[0538] This result shows that styrene sulfonate, Na salt does notpromote the RF activation of acrylic resin, with and without glycerin.

[0539] A second composition included: KELSOL 5243 polyester   2 partsCYMEL 0.6 parts Vinyl sulfonic acid, Na salt At 25% in water 0.5 parts

[0540] The above composition was evaluated as before at 700 mV and 2.5minutes. The gel content was found to be 67.2%. Similar compositionwithout susceptor had a gel content of 73.7% (see above). This resultshows that addition of vinyl sulfonic, Na salt, does not promote RFactivation of polyester resin.

[0541] 10% Glycerin was added to the above composition. The resultantcomposition was evaluated as before under 700 mV and 1 second RF field.The sample became too hot and burst into flames. The result shows thatglycerin does activate under high field and it is possible to get highdegree of crosslinking reaction under very short times, say less than 1second.

[0542] A third composition included: MAINCOTE HYDUR acrylic 1 partEastman AD 35 D polyester susceptor 1 part

[0543] The above composition was evaluated as before and the gel contentwas found to be 79.2% at 700 mV and 2.6 minutes. The same compositionwithout the susceptor had a gel content of 81.8% at 700 mV and 2.5minutes exposure (see above). In this case addition of a susceptor doesnot have any effect on RF activation of acrylic polymer.

[0544] 10% Glycerin was added to the third composition which was exposedto 700 mV for 2 minutes. This exposure led to a very violent reaction.This shows that susceptor was too active.

[0545] The third composition was exposed to 500 mV for 5 minutes. Gelcontent was found to be 68.4%. A comparable sample without the additionof susceptor was found to give a gel content of 61.5% after 2.5 minutesexposure (see above). The result shows that the susceptor had verylittle effect.

[0546] The third composition comprising 10% glycerin was evaluated at500 mV and 5 minutes. The gel content was found to be 69.7%. The samesample with out susceptor had a gel content of 92.3% at 500 mV and 2.5minute exposure (see above). The result shows that the addition ofsusceptor had a negative effect on RF activation.

[0547] It appears addition of known susceptors to the various thermosetresin compositions has very little impact on RF activation of theresins. In some cases, it seems to have a negative impact.

[0548] In a few cases, the heat generation is quite violent suggestingthat proper tuning of frequency/power/time and other variables will leadto conditions that would allow very short cure times.

Example 14

[0549] The use of the carboxyl containing diol dimethylol butanoic acidwas tested as a susceptor. The composition included: Formerez 11-36  3.2parts DESMODUR W 0.75 parts Dimethylol Butanoic acid 0.28 parts T-12catalyst 1-2 drops

[0550] No significant activation took place when this composition wasexposed to 500 mV level (2.5 and 5 minute exposure).At 5 minute exposureunder 700 mV, the glass slide broke and no data could be gathered. Asnoted above, under similar conditions without the susceptor, a gelcontent of 11.4% was obtained in the absence of glycerin and 27% in thepresence of glycerin.

[0551] It may be useful to add the acid diol in N-methyl pyrrolidone oranother polar solvent and neutralize with a tertiary amine to protonatethe acid. Further use of urethane prepolymer containing carboxyl orsulfonate groups in the presence of a tertiary amine (to protonate theacid) may be a better susceptor candidate for the urethane reaction.

Example 15

[0552] This example demonstrates a method of selectively activating thecompositions of the invention within a multi-layer stack of materials.

[0553] The composition comprised 70 wt % Eastman AQ35S sulfopolyester in30 wt % glycerin. The composition was applied and dried down from anaqueous dispersion to form a continuous 0.003 inch thick film on oneside of a bilaminate polyolefin material. The bilaminate polyolefinmaterial comprised a single layer of polypropylene (PP) non-wovenmaterial bonded to a single layer of polyethylene (PE) film. Thecomposition was coated onto the PP side of the bilaminate material. Thecoated bilaminate-material was then interposed between two multi-layerstacks of un-coated bilaminate material to form a composite sandwich ofmaterials. Each multi-layer stack had two layers of the un-coatedbilaminate polyolefin material. The composite sandwich (410) was thenplaced directly over the RF probes and compressed under a TEFLON™ blockat 30 psi. The composition was RF heated by applying approximately 1 kWof forward power into the tuned heat station 4122 for 200 millisecondsat approximately 13.5 MHz. After applying the RF energy to the compositesandwich, the pressure was removed and the sandwich was evaluated byslowly pulling the layers apart by hand. Every layer was easily pulledapart, with no observed bonding, except for the two layers that were indirect contact with the bonding composition. The two layers that were indirect contact with the bonding composition were firmly adhered by thebonding composition. As a control experiment, the experiment wasrepeated, except that no RF energy was applied to the compositesandwich. This experiment resulted in no observable bonding between anyof the layers, including the two layers that were in direct contact withthe bonding composition. It should be understood that in thisexperiment, the bonding composition was pre-applied to one surface ofone of the layers of the composite sandwich. The bonding compositioncould be applied to more than one surface of more than one layer.Bonding would occur between any layers that are each in contact with agiven layer of bonding composition.

Example 16

[0554] This example demonstrates the method of interfacing a carrierlayer onto the surface of a susceptor layer to achieve an RF heatablecomposition. First, a 0.003 inch layer of a sulfonated polyestercopolymer, Eastman AQ35S (Supplied by Eastman Chemical Company,Kingsport. Tenn.) was coated out of an aqueous dispersion onto thepolypropylene (PP) non-woven side of a bilaminate web consisting of alayer of PP non-woven bonded to a layer of polyethylene (PE) film. Thecoating was thoroughly dried down under a heat lamp and fan. A sandwichwas made by placing a sample of the coated web against the PP side of asecond piece of the same web material which was not coated, such thatthe coating was between the two webs. The sandwich was placed directlyover the RF probes (410) of the RF set-up described in FIG. 41. Thedistance between the RF probes and the sandwich was about 0.010 inch;The sandwich layers were pressed firmly together against the RF probeswith 35 psi of applied pressure. About 1 kW of 13.5 MHz RF energy wasapplied for 500 milliseconds and resulted in no noticeable heating orbonding between the webs. Then the sandwich layers were separated andthe susceptor coating was moistened with distilled water. The sandwichwas re-assembled and RF energy was applied to it for 500 milliseconds asdescribed above, resulting in very good bonding of the webs. As acontrol experiment, a sandwich consisting of two webs of the uncoatedweb material was prepared by moistening the PP side of each web andbringing the water moistened surfaces together. RF energy was appliedfor 500 milliseconds to the sandwich in the same way described above,resulting in no noticeable heating.

Example 17

[0555] This example demonstrates the effect of varying the concentrationof the polar carrier in blends of the polar carrier and an ionomer. Thepolar carrier of this example is glycerin. Glycerin has a dielectricconstant, e, of 42.5 at 25° C. The ionomer of this example is acommercially available sulfonated polyester ionomer (Eastman AQ55S).

[0556] Several compositions were prepared as hot-melt blends of AQ55Sand glycerin. The wt. % concentration of glycerin in the compositionswas varied from 10% to 70. The compositions were prepared as follows:

[0557] Each composition was prepared to have a total mass of 50 grams.For each composition, the respective amounts of AQ55S pellets andglycerin were initially weighed into a resin flask and mixed to achievethorough wetting of the resin pellets with the glycerin. The flask wasthen fit with a condenser column and sealed stir-assembly, and partiallyimmersed into a 335 F hot oil bath to achieve controlled heating andmelting of the mixture. After the pellets became molten and swollen withthe glycerin, the mixture was stirred and blended into a uniformcomposition.

[0558] Each composition was then applied in its molten state as a 0.003inch thick×1 inch wide×5 inch long, continuous layer along the centerline of a 4 inch wide×0.0035 inch thick sheet of transparency film (3MPP2500 Transparency Film) and allowed to set-up at room temperature.Several such draw downs were made for each composition. A twin bladesample cutter was used to cut strips from the draw downs, by cuttingacross and perpendicular to the 5 inch long center line of each of thedraw downs. This produced 1 inch wide×4 inch long strips of acetatefilm, each with a 1 inch×1 inch×0.003 inch thick coating of compositionin the center and 1½ inch long tails on each end. The resulting coatingsdiffered in their relative RF-heating properties as well as theirrelative heat resistance to bond failure in a given shear loadingcondition.

[0559] RF-heating of each composition was evaluated as follows. For eachcomposition, several sandwiches were prepared. Each sandwich was made byplacing the polypropylene (PP) non-woven side of a 1 inch wide×4 inchlong strip of a bilaminate web against the coated side of the coatedacetate test strip. The bilaminate web was composed of a layer of PPnon-woven bonded to a layer of polyethylene (PE) film. Each sandwich wasplaced directly over the RF probes (410) of the RF set-up described inFIG. 41, such that the uncoated side of the acetate test strip wasplaced toward the probes. The sandwich layers were pressed firmlytogether against a layer of 0.010 inch thick layer of TEFLON™ andacetate that separated the RF probes and sandwich. A single pulse of 0.5kW, 13.5 MHz RF energy was applied for a controlled duration to eachsandwich. For each composition several sandwiches were activated, eachat an incrementally longer duration. This gave a range of RF heatingresults. Threshold RF activation was determined from each range ofresults as the minimum duration that result in sufficient melting andwetting of the adhesive coating to the web to be observed by the nakedeye. Threshold RF activation by the specific RF set-up (generallyindicated in FIG. 41) resulted in a narrow band of heating that wasbiased toward and parallel to the “high” probe of the probe assembly(602 or 604). This was because an “unbalanced” impedance matchingnetwork was used in the set-up.

[0560] Resistance to shear load bond failure was evaluated as follows,For each composition, bonded specimens were prepared. The specimens eachconsisted of a sandwich of a 1 inch×4 inch×0.0035 inch thick layer ofacetate pressed against and hot-melt bonded to the coated side of acoated acetate test strip. (The coated acetate test strips were preparedas described earlier in this example.) Each hot-melt bond wasfacilitated by pressing the sandwich on a 275 F hot plate surface undera 0.5 Kg load for 30 seconds, and then removing the sandwich andallowing it to cool and solidify into a bonded specimen. Each sandwichhad a pair of “tails” of unbonded acetate on each side of a centered 1inch×1 inch bonded area of the sandwich. One tail from each of the twopairs and on opposite sides of the sandwich was cut off. This resultedin the final bonding specimen, consisting of two 1 inch×3 inch layers of0.0035 inch thick acetate bonded together across a 1 inch by 1 inchoverlap by an interposed 0.003 inch thick layer of the composition beingtested. The specimens were then placed under a shear load of 0.5 Kg in atemperature controlled chamber at 100 F. The time required to result intotal bond failure (disassembly of the specimen) at 100 F was measuredfor each specimen and is referred to herein as “Shear Holding Time”.

[0561] The following observations were made:

[0562] (1) As the percentage of glycerin was increased from 10% to 70%,a sharp increase in relative rates of RF heating began to occur at about10% glycerin. (See FIG. 54.)

[0563] (2) As the percentage of glycerin was decreased from 70% to 10% asharp increase in relative heat resistance began to occur at about 30%glycerin. (See FIG. 55.)

Example 18

[0564] This example demonstrates the effect of varying the concentrationof the polar carrier in blends of the polar carrier and an alternativesulfonated polyester ionomer to the AQ55S of Example 17. The polarcarrier of this example is glycerin. Glycerin has a dielectric constantof 42.5 at 25° C. The ionomer of this example is a commerciallyavailable sulfonated polyester ionomer (Eastman AQ35S).

[0565] Several compositions were prepared as hot-melt blends AQ35S andglycerin. The wt. % concentration of glycerin in the compositions wasvaried from 10% to 70%.

[0566] The compositions were prepared as follows:

[0567] Each composition was prepared to have a total mass of 50 grams.For each composition, the respective amounts of AQ35S pellets andglycerin were initially weighed into a resin flask and mixed to achievethorough wetting of the resin pellets with the glycerin. The flask wasthen fit with a condenser column and sealed stir-assembly, and partiallyimmersed into a 335 F hot oil bath to achieve controlled heating andmelting of the mixture. After the pellets became molten and swollen withthe glycerin, the mixture was stirred and blended into a uniformcomposition.

[0568] RF-heating and resistance to shear load bond failure wasevaluated for each composition as described in Example 17.

[0569] The following observations were made:

[0570] (1) As the percentage of glycerin was increased from 10% to 30%,a sharp increase in relative rates of RF heating began to occur at about10% glycerin. (See FIG. 56.)

[0571] (2) As the percentage of glycerin was decreased from 30% to 20% asharp increase in relative heat resistance began to occur at about 30%glycerin. (See FIG. 57.) These results agreed closely with the resultsof Example 17.

Example 19

[0572] This example demonstrates the effects of dielectric constant andconcentration of various polar carriers on the ability to achievesignificantly improved RF activation times in compositions comprisingblends of ionomers and polar carriers, as compared to compositionscomprising the ionomer without sufficient presence of polar carrier.

[0573] The polar carriers and respective measured dielectric constantsof this example are:

[0574] (1) Propylene carbonate; ε=62.67 at 25° C.

[0575] (2) Glycerin; ε=42.5 at 25° C.

[0576] (3) N-methyl-2-pyrrolidone; ε=32.2 at 20° C.

[0577] (4) 1,2-propyleneglycol ε=32 at 25° C.

[0578] (5) Polyethylene glycol 200; ε=17.70 at 23.5° C.

[0579] (6) Benzoflex 9-88 (dipropylene glycol benzoate); ε=12.28 at 25°C.

[0580] The ionomer of this example is a commercially available 30%solids aqueous dispersion of sulfonated polyester ionomer (EastmanAQ35D). Several compositions were prepared as aqueous mixtures of AQ35Dand each of the polar carriers. The wt. % concentration of polar carrierin each of the compositions was varied from 0% up to 50%, where totalweight is based on total weight of ionomer solids combined with totalweight of polar carrier.

[0581] The compositions were prepared as follows:

[0582] Each composition was prepared to have a total mass of 50 grams.For each composition, the respective amounts of AQ35D ionomer dispersionand glycerin were initially weighed into ajar and mixed for about 10minutes. The jars were sealed with tops until castings were made.

[0583] Each composition was then applied as a liquid at room temperatureinto castings onto a 0.0035 inch thick sheet of transparency film (3MPP2500 Transparency Film) and allowed to dry down into 0.003 inch thickcoatings. The resulting coatings differed in their relative RF-heatingproperties. RF activation was evaluated as described in Example 17.

[0584] The following observations were made:

[0585] As the percentage of each polar carrier was increased from 0% to50%, a sharp increase in relative rates of RF heating began to occur atabout 10% glycerin (except for the composition that was prepared fromBenzoflex 9-88, which experienced a relatively slow and gradualincrease). (See FIG. 58.).

[0586] While Benzoflex 9-88 gave a compatible composition with the AQ35Spolymer, it resulted in a significantly less RF-active composition thanany of the compositions that were prepared from more polar materialswith relatively high dielectric constants. (See FIG. 58.).

Example 20

[0587] This example demonstrates the effect of varying the concentrationof a microcrystalline wax in the composition, X % (80% AQ55S/20%Glycerin)/Y % wax. The microcrystalline wax in this example was PARICIN220 [N-(2-hydroxyethyl)-12-hydroxystearamide].

[0588] The compositions were prepared as follows:

[0589] Each composition was prepared to have a total mass of 50 grams. A300 gram batch of 80% AQ55S/20% glycerin was prepared. 240 grams ofAQ55S pellets and 60 grams of glycerin were initially weighed into aresin flask and mixed to achieve thorough wetting of the resin pelletswith the glycerin. The flask was then fit with a condenser column andsealed stir-assembly, and partially immersed into a 335 F hot oil bathto achieve controlled heating and melting of the mixture. After thepellets became molten and swollen with the glycerin, the mixture wasstirred and blended into a uniform composition. After a total of 4 hoursof heating, the flask was removed from the hot oil bath. Several glassjars were each filled with 20 grams of the molten composition.Incrementally increasing amounts of PARICIN 220 were weighed into thehot contents of each jar, to result in a concentration series of X %(80% AQ55S/20% Glycerin)/Y % PARICIN 220, where Y=0, 1, 2, 3,4, 5, 10,15, 20, 25 and 30, and X=100−Y. Each open jar was placed in an oven at300 F for 30 minutes and allowed to become molten. The molten contentswere then hand stirred with wooden stir sticks for 2 minutes to form asmooth and uniform blend.

[0590] Each-composition was then applied in its molten state as a 0.003inch thick×1 inch wide×5 inch long, continuous layer along the centerline of a 4 inch wide×0.0035 inch thick sheet of transparency film (3MPP2500 Transparency Film) and allowed to set-up at room temperature.Several such draw downs were made for each composition. A twin bladesample cutter was used to cut strips from the draw downs, by cuttingacross and perpendicular to the 5 inch long center line of each of thedraw downs. This produced 1 inch wide×4 inch long strips of acetatefilm, each with a 1 inch×1 inch×0.003 inch thick coating of compositionin the center and 1½ inch long tails on each end.

[0591] The resulting coatings differed in their relative RF-heatingproperties and melt viscosities.

[0592] RF-heating was evaluated for each composition as described inExample 17. The Brookfield viscosity of each composition was measured at275 F, using an S27 spindle.

[0593] The following observations were made:

[0594] As the wt % of PARICIN 220 was increased from 0 to 10%, there wasa slight increase (<5%) in the time required to heat each composition tothe same degree as required at 0% PARICIN 220. As the wt % of PARICIN220 was increased from 10% to 30%, there was a significant increase inthe time required to heat each composition to the same degree asrequired at 0% PARICIN 220. (See FIG. 59.).

[0595] As the wt % of PARICIN 220 decreased from 10% to 0%, the meltviscosity at 275 F increased by a factor of 6 from 6800 cP to 42000 cP.

Example 21

[0596] This example demonstrates the effect of varying the concentrationof the polar carrier in blends of the polar carrier and an ionomer,where the ionomer is the sodium salt of an ethylene acrylic acidcopolymer. The polar carrier of this example is glycerin. Glycerin has adielectric constant, ε, of 42.5 at 25° C. The ionomer of this example isa commercially available aqueous dispersion of the sodium salt of anethylene acrylic acid copolymer (MICHEM 48525P).

[0597] Several compositions were prepared as aqueous mixtures of MICHEM48525P and glycerin. The wt. % concentration of glycerin in each of thecompositions was Xvaried from 0% up to 50%, where total weight is basedon total weight of ionomer solids combined with total weight ofglycerin.

[0598] The compositions were prepared as follows:

[0599] Each composition was prepared to have a total mass of 50 grams.For each composition, the respective amounts of MICHEM 48525P ionomerdispersion and glycerin were initially weighed into a jar and mixed forabout 10 minutes. The jars were sealed with tops until castings weremade. Each composition was then applied as a liquid at room temperatureinto castings onto a 0.0035 inch thick sheet of transparency film (3MPP2500 Transparency Film) and allowed to dry down into 0.003 inch thickcoatings. The resulting coatings differed in their relative RF-heatingproperties. RF activation was evaluated as described in Example 17.

[0600] The following observations were made:

[0601] As the percentage of each polar carrier was increased from 0% to50%, a sharp increase in relative rates of RF heating began to occur atabout 10% glycerin (See FIG. 61). This result agrees well with theresults of Examples 17, 18 and 19.

Example 22

[0602] This example demonstrates the relative heat resistance to bondfailure in a given shear loading condition of four separate compositionsthat are composed of four different sulfonated polyesters respectively(AQ14000, AQ35S, AQ48S and AQ55S) and the same polar material in eachcase(glycerin). The polar carrier of this example is glycerin. Glycerinhas a dielectric constant, ε, of 42.5 at 25° C. The ionomers of thisexample are commercially available sulfonated polyester ionomers(Eastman AQ14000, AQ35S, AQ48S and AQ55S).

[0603] The four compositions were prepared to have 80 wt % ionomer/20 wt% glycerin. Each composition was prepared to have a total mass of 50grams. For each composition, the respective amounts of ionomer pelletsand glycerin were initially weighed into a resin flask and mixed toachieve thorough wetting of the resin pellets with the glycerin. Theflask was then fit with a condenser column and a sealed stir-assembly,and then partially immersed into a 335 F hot oil bath to achievecontrolled heating and melting of the mixture. After the pellets becamemolten and swollen with the glycerin, the mixture was stirred andblended into a uniform composition.

[0604] Each composition was then applied in its molten state as a 0.003inch thick×1 inch wide×5 inch long, continuous layer along the centerline of a 4 inch wide×0.0035 inch thick sheet of transparency film (3MPP2500 Transparency Film) and allowed to set-up at room temperature.Several such draw downs were made for each composition. A twin bladesample cutter was used to cut strips from the draw downs, by cuttingacross and perpendicular to the 5 inch long center line of each of thedraw downs. This produced 1 inch wide×4 inch long strips of acetatefilm, each with a 1 inch×1 inch×0.003 inch thick coating of compositionin the center and 1½ inch long tails on each end. The resulting coatingswere each evaluated for their relative RF-heating properties as well astheir relative heat resistance to bond failure in a given shear loadingcondition, as described in Example 17.

[0605] The following observations were made for the four compositions:

[0606] 80% AQ14000/20% Glycerin

[0607] Tg of AQ14000=7° C.

[0608] Threshold RF Activation Time=130 ms

[0609] Shear Holding Time=1,604 sec

[0610] 80% AQ35S/20% Glycerin

[0611] Tg of AQ35S=35° C.

[0612] Threshold RF Activation Time=310 ms

[0613] Shear Holding Time=68,252 sec

[0614] 80% AQ48S/20% Glycerin

[0615] Tg of AQ48S=48° C.

[0616] Threshold RF Activation Time=90 ms

[0617] Shear Holding Time=40,346 sec

[0618] 80% AQ55S/20% Glycerin

[0619] Tg of AQ55S=55° C.

[0620] Threshold RF Activation Time=100 ms

[0621] Shear Holding Time=1,450,000 sec

Example 23

[0622] This example demonstrates a hot melt composition prepared from asulfonated polyester ionomer (AQ55S) and a polar plasticizer (RIT-CIZER#8). The composition was prepared to have 80 wt % ionomer/20 wt %RIT-CIZER #8. The composition was prepared to have a total mass of 50grams. The respective amounts of ionomer pellets and glycerin wereinitially weighed into a resin flask and mixed to achieve thoroughwetting of the resin pellets with the glycerin. The flask was then fitwith a condenser column and a sealed stir-assembly, and then partiallyimmersed into a 335 F hot oil bath to achieve controlled heating andmelting of the mixture. After the pellets became molten and swollen withthe glycerin, the mixture was stirred and blended into a uniformcomposition. The composition was then applied in its molten state as a0.016 inch thick×1 inch wide×1 inch long, continuous layer along thecenter line of a 4 inch wide×0.0035 inch thick sheet of transparencyfilm (3M PP2500 Transparency Film). The resulting coating was evaluatedfor relative RF-heating as described in Example 17.

[0623] The following observations were made for the composition:

[0624] The composition was very thick and stiff at 335° F. It was notpossible to measure the Brookfield viscosity at 275° F. At roomtemperature, the composition was clear, tough and brittle. There seemedto be very good compatibility between the polymer and RIT-CIZER #8. Thethreshold RF activation time was measured to be approximately 4 seconds.

Example 24

[0625] This example demonstrates a composition that comprises anionomer-type susceptor, a polar material and an adhesive compound.First, several different RF susceptor compositions were prepared byblending various ionomers and polar material. Then, each of the RFsusceptor compositions were blended with an adhesive compound.

[0626] Preparation of the RF-Susceptor Compositions:

[0627] Several different RF susceptor compositions were prepared byblending various commercially available sulfonated polyester ionomers(Eastman AQ35 S, AQ48S and AQ55S, AQ1045, AQ1350, AQ14000) with a polarmaterial (glycerin). The RF-susceptor compositions of this exampleinclude but are not limited to:

[0628] 70 wt % AQ35S/30 wt % Glycerin

[0629] 70 wt % AQ48S /30 wt % Glycerin

[0630] 70 wt % AQ55S/30 wt % Glycerin

[0631] 70 wt % AQ1045/30 wt % Glycerin

[0632] 70wt %AQ1350/30wt %Glycerin

[0633] 70 wt % AQ 14000/30 wt % Glycerin.

[0634] Each RF-susceptor composition was prepared to have a total batchmass of 300 grams. For each composition, the respective amounts ofionomer and glycerin were initially weighed into a resin flask and mixedto achieve thorough wetting of the resin pellets with the glycerin. Theflask was then fit with a condenser column and sealed stir-assembly, andpartially immersed into a 335 F hot oil bath to achieve controlledheating and melting of the mixture. After the polymer became molten andswollen with the glycerin, the mixture was stirred and blended into auniform composition. The compositions that comprised linear polymers(AQ35S, AQ48S and AQ55S) were each blended at 335 F for 3 hours. Thecomposition comprising AQ1045 was blended at 335 F for 1 hour. Thecompositions comprising AQ 1350 and 14000 were each blended at 335 F for1.5 hours. Each of the RF-susceptor compositions was cooled and storedat room temperature for later use.

[0635] Preparation of the Compositions Comprising Blends of RF-SusceptorCompositions and an Adhesive Compound:

[0636] Each of the RF susceptor compositions was blended with anadhesive compound. The adhesive compound of this example is a randomcopolymer of ethylene vinyl acetate (EVA). The commercially availableEVA that was used is DuPont Polymer's ELVAX 210, Lot #90204492.

[0637] Each composition was prepared to have a total mass of 17 grams.For each composition, 7 grams of ELVAX 210 and 10 grams of therespective RF-susceptor composition was added to a glass jar at roomtemperature. The open jar was then heated in a convection oven at 335 Ffor 40 minutes. After 40 minutes of heating, the jar was removed fromthe oven to the surface of a 330 F hot plate and stirred by hand for 1minute to result in a uniform smooth blend.

[0638] A total of six compositions were prepared. TheRF-susceptor/Adhesive compositions of this example include but are notlimited to:

[0639] A. 41wt % AQ35S/18wt % Glycerin/41wt % ELVAX210

[0640] B. 41 wt % AQ48S/18 wt % Glycerin/41 wt % ELVAX 210

[0641] C. 41 wt % AQ55S/18 wt % Glycerin/41 wt % ELVAX 210

[0642] D. 41 wt % AQ1045/18 wt % Glycerin /41 wt % ELVAX 210

[0643] E. 41 wt % AQ1350/18 wt % Glycerin! 41 wt % ELVAX 210

[0644] F. 41 wt % AQ14000/18 wt % Glycerin 41 wt % ELVAX 210

[0645] Evaluation of the Blends of RF-Susceptor Compositions with ELVAX210.

[0646] Immediately after stirring the composition into a uniform blend,each composition was then applied in its molten state as a 0.003 inchthick×1 inch wide×5 inch long, continuous layer along the center line ofa 4 inch wide×0.0035 inch thick sheet of transparency film (3M PP2500Transparency Film) and allowed to set-up at room temperature. Severalsuch draw downs were made for each composition. A twin blade samplecutter was used to cut strips from the draw downs, by cutting across andperpendicular to the 5 inch long center line of each of the draw downs.This produced 1 inch wide×4 inch long strips of acetate film, each witha 1 inch×1 inch×0.003 inch thick coating of composition in the centerand 1½ inch long tails on each end.

[0647] The resulting coatings were each evaluated for their relativecoat properties as well RF-heating properties, as described in Example17.

[0648] The following observations were made for the six compositions:TABLE 11 Coating Properties RF Com- Activation position ToughnessClarity Color Tackiness Time (ms) A Soft Translucent White Slight Tack520 B Tough Translucent White Tacky 100 C Very Tough Translucent WhiteVery Slight 280 Tack D Very Soft Clear None Tacky 430 E Soft Clear NoneTacky 380 F Soft Clear None Tacky 340

Example 25

[0649] This example demonstrates compositions comprising an ionomer, apolar material and various low molecular weight polyolefin additives.

[0650] First, an RF heatable hot melt composition was prepared byblending 70 wt % AQ35 (a sulfonated polyester, commercially availablefrom Eastman Chemical Company) with 30 wt % glycerin for about 3 hoursat 335 F. Then, several compositions were prepared by blending smallsamples of the molten AQ35/glycerin blend, separately with variousgrades of EPOLENE (low molecular weight polyolefins, commerciallyavailable from Eastman Chemical Company).

[0651] The polyolefin polymers of this example are Eastman Chemical's:EPOLENE N-10 (lot #11478), EPOLENE N-11 (lot #89352), EPOLENE N-14 (lot#12877), EPOLENE N-15 (lot #491104), EPOLENE N-20 (lot #87023), EPOLENEN-21 (lot #13018), and EPOLENE N-34 (lot #12710). EPOLENE polymers arelow molecular-weight polyolefins that can be useful as base polymers forhot-melt adhesives.

[0652] Each composition was then applied in its molten state as a 0.003inch thick×1 inch wide×5 inch long, continuous layer along the centerline of a 4 inch wide×0.0035 inch thick sheet of transparency film (3MPP2500 Transparency Film) and allowed to set-up at room temperature.Several such draw downs were made for each composition. A twin bladesample cutter was used to cut strips from the draw downs, by cuttingacross and perpendicular to the 5 inch long center line of each of thedraw downs. This produced 1 inch wide×4 inch long strips of acetatefilm, each with a 1 inch×1 inch×0.003 inch thick coating of compositionin the center and 1½ inch long tails on each end.

[0653] The resulting coatings were each evaluated for their relativeRF-heating properties as well as their relative heat resistance to bondfailure in a given shear loading condition, as described in Example 17.

[0654] Table 12 summarizes the observations that were made for thevarious compositions: TABLE 12 EPOLENE# mw viscosity rftime hangtime 70%AQ35/30% Glycerin + 5% EPOLENE N-10 10000 8675 210 3.91 N-11 6000 7450210 2.99 N-14 4000 7750 220 4.77 N-15 12000 13500 210 2.60 N-20 1500010020 220 6.01 N-21 6500 6125 210 1.91 N-34 6200 8100 210 2.95 70%AQ35/30% Glycerin + 10% EPOLENE N-10 10000 10220 250 3.30 N-11 6000 7975240 1.94 N-14 4000 8725 250 3.33 N-15 12000 17900 250 1.46 N-20 150009450 240 2.28 N-21 6500 7112 240 1.59 N-34 6200 8212 240 1.78 70%AQ35/30% Glycerin + X % EPOLENE N-10 % EPOLENE viscosity rftime hangtime0 6362 200 4.46 2.5 8337 210 2.10 5 8675 210 3.91 10 10220 250 3.30 1511570 280 5.03 20 12250 280 5.99 25 14620 300 7.55 30 15250 825 5.35

Example 26

[0655] This example demonstrates a series of compositions that comprise:9% polyethylene glycol and 91% (75% AQ55/25% glycerin).

[0656] First, a blend of 75% AQ55 and 25% glycerin was made by blendingAQ55 and glycerin for 3 hours at 335 F. Then, a series of compositionswas prepared in which each composition was prepared as a molten blend of9% polyethylene glycol (PEG) and 91% (75% AQ55/25% glycerin).

[0657] Each composition was then applied in its molten state as a 0.003inch thick×1 inch wide×5 inch long, continuous layer along the centerline of a 4 inch wide×0.0035 inch thick sheet of transparency film (3MPP2500 Transparency Film) and allowed to set-up at room temperature.Several such draw downs were made for each composition. A twin bladesample cutter was used to cut strips from the draw downs, by cuttingacross and perpendicular to the 5 inch long center line of each of thedraw downs. This produced 1 inch wide×4 inch long strips of acetatefilm, each with a 1 inch×1 inch×0.003 inch thick coating of compositionin the center and 1½ inch long tails on each end. The resulting coatingswere each evaluated for their relative RF-heating properties as well astheir relative heat resistance to bond failure in a given shear loadingcondition, as described in Example 17.

[0658] Table 13 summarizes the observations that were made for thevarious compositions: TABLE 13 hangtime PEG # tack Rftime hrs for 1 sq.inch (PEG200 Brookfield 1 = very slight time required bond area to failat through Viscosity tack; 2 = slight to melt sample 100 F. under a 0.5kg PEG8000) (cP at 275 F.) tack; 3 = tacky (ms). shear load. 200 15650 1130 12.94 300 12500 1 150 11.35 400 14600 1 130 5.34 600 13700 3 1407.23 900 12250 1 150 5.76 1000 12800 1 150 6.82 1450 11700 1 210 4.853350 15070 1 200 5.70 4000 14620 2 250 5.51 4600 16400 2 220 9.34 800017320 1 230 6.35

Example 27

[0659] This example demonstrates a composition comprising 10% IGEPAL (acommercially available additive from Rhodia) and 90% (75% AQ55/25%glycerin).

[0660] A first composition comprising 75% AQ55 and 25% glycerin wasprepared by blending AQ55 and glycerin for 6 hours at 335 F. A secondcomposition was prepared by blending IGEPAL CO-880 at 10 wt % with asample of the first composition.

[0661] Each composition was then applied in its molten state as a 0.003inch thick×1 inch wide×5 inch long, continuous layer along the centerline of a 4 inch wide×0.0035 inch thick sheet of transparency film (3MPP2500 Transparency Film) and allowed to set-up at room temperature.Several such draw downs were made for each composition. A twin bladesample cutter was used to cut strips from the draw downs, by cuttingacross and perpendicular to the 5 inch long center line of each of thedraw downs. This produced 1 inch wide×4 inch long strips of acetatefilm, each with a 1 inch×1 inch×0.003 inch thick coating of compositionin the center and 1½ inch long tails on each end.

[0662] The resulting coatings were each evaluated for their relativeRF-heating properties as well as their relative heat resistance to bondfailure in a given shear loading condition, as described in Example 17.

[0663] Table 14 summarizes the observations that were made for thevarious compositions: TABLE 14 RF Activation Time Viscosity Timerequired to melt the Composition (cP at 275 F.) sample (ms).  5%AQ55/25% glycerin 28,200 180 90% (AQ55/glycerin)/ 9,750 360 10% IGEPALCO-880

Example 28

[0664] This example demonstrates an RF heatable composition comprising75% AQ48 (a commercially available sulfonated polyester from EastmanChemical Company) and 25% glycerin.

[0665] The composition was prepared by blending 75 wt % AQ48 with 25 wt% glycerin for 4 hours at 335 F. The resulting molten composition wasfluid and clear. When this composition was cast onto layers of acetateand allowed to cool, the resulting solid draw-downs were clear and hadcold-tack. This composition is ideal for applications where parts are tobe initially adhered with a green strength bond by the composition andsubsequently fused by the heat that is generated from within thecomposition as it is exposed to RF energy.

[0666] The molten composition had a Brookfield viscosity of 5,750 cP at275 F, using an S27 spindle at 20 RPM. The composition was then appliedin its molten state as a 0.003 inch thick×1 inch wide×5 inch long,continuous layer along the center line of a 4 inch wide×0.0035 inchthick sheet of transparency film (3M PP2500 Transparency Film) andallowed to set-up at room temperature. Several such draw downs weremade. A twin blade sample cutter was used to cut strips from the drawdowns, by cutting across and perpendicular to the 5 inch long centerline of each of the draw downs. This produced 1 inch wide×4 inch longstrips of acetate film, each with a 1 inch×1 inch×0.003 inch thickcoating of composition in the center and 1½ inch long tails on each end.The resulting coatings were each evaluated for their RF-heatingproperties, as described in Example 17. RF activation was achieved in160 ms.

[0667] The composition was then drawn into flat beads (0.10 inches wideby 0.01 inches thick at the maximum thickness—the beads were crowned inthe middle and feathered at the edges). Three sandwiches of materialswere made. Each sample was made by placing a single bead of thecomposition between two identical layers of thin-film bilaminatepolyolefin material. Each layer of bilamninate material was composed oftwo layers—one layer of polypropylene non-woven (PP) and one layer ofpolyethylene film (PE).

[0668] The first sandwich (sample 1) was assembled such that the beadwas in direct contact with the PP side of one of the layers ofbilaminate, and the PP side of the other layer of bilaminate. The secondsandwich (sample 2) was assembled such that the bead was in directcontact with the PP side of one of the layers of bilaminate, and the PEside of the other layer of bilaminate. The third sandwich (sample 3) wasassembled such that the bead was in direct contact with the PE side ofone of the layers of bilaminate, and the PE side of the other layer ofbilaminate.

[0669] In each case, the bead had slight tack and was able to gentlyhold the layers of the sandwich together. Each sandwich was thenactivated in a 13.5 MHz RF field for 200 ms at 1000 watts. In each case,melting of the bilaminate layers had occurred. Then the sandwiches wereeach immersed and washed in MEK for several minutes in order to removethe adhesive from the bond line. In each case, after washing theadhesive from the sandwich, residual bonding was observed between alllayers of the sandwich in the areas where melting had been observed.

[0670] While various embodiments of the present invention have beendescribed above, it should be understood that they have been presentedby way of example only, and not limitation. Thus, the breadth and scopeof the present invention should not be limited by any of theabove-described exemplary embodiments, but should be defined only inaccordance with the following claims and their equivalents.Additionally, all patents, patent applications and publicationsmentioned above are incorporated by reference herein.

What is claimed is:
 1. A composition for use in adhesion or bonding,comprising: a susceptor; and a polar carrier, wherein said susceptorand/or said polar carrier are present in amounts effective to allow saidcomposition to be heated by radio frequency (RF) energy, with theproviso that said susceptor is not a quaternary ammonium salt and thatsaid polar carrier comprises about 13 to about 30 weight percent of thecomposition with respect to said susceptor.
 2. A composition for use incoating, comprising: a susceptor; and a polar carrier, wherein saidsusceptor and/or said polar carrier are present in amounts effective toallow said composition to be heated by RF energy, with the proviso thatsaid susceptor is not a quaternary ammonium salt and that said polarcarrier comprises about 13 to about 30 weight percent of the compositionwith respect to said susceptor.
 3. A composition for use in adhesion,bonding or coating, consisting essentially of: a susceptor; and a polarcarrier, wherein said susceptor and/or said carrier are present inamounts effective to allow said composition to be heated by RF energyand that said polar carrier comprises about 13 to about 30 weightpercent of the composition with respect to said susceptor.
 4. Thecomposition of any one of claims 1-3, wherein the susceptor and thecarrier are substantially blended with one another and form a mixture.5. The composition of any one of claims 1-3, wherein the susceptor andthe carrier are disposed on one another.
 6. The composition of any oneof claims 1-3, wherein the susceptor is an ionic compound.
 7. Thecomposition of any one of claims 1-3, wherein the susceptor is a polarcompound having a sufficiently high dipole moment that molecularoscillations or vibrations of the compound occur when exposed to RFenergy.
 8. The composition of any one of claims 1-3, wherein the polarcarrier has a dielectric constant of 13-63 (25° C.)
 9. The compositionof any one of claims 1-, further comprising or consisting essentially ofan adhesive compound, wherein said adhesive compound, said susceptor andsaid polar carrier are blended substantially with one another to formsaid mixture.
 10. The composition of claim 9 , wherein said adhesivecompound and said susceptor are an ionomer.
 11. The composition of anyone of claims 1-3, wherein said susceptor comprises or consistsessentially of an aqueous dispersion of a sulfopolyester adhesive. 12.The composition of claim 11 , wherein said sulfopolyester adhesive ispresent at a concentration of from about 5% to about 75%.
 13. Thecomposition of any one of claims 1-3, wherein said susceptor is one ormore ionic salts and is present in the form of a precipitate.
 14. Thecomposition of any one of claims 1-3, wherein said susceptor is anionomeric polymer.
 15. The composition of claim 14 , wherein saidionomeric polymer is a sulfonated polyester or copolymer thereof, orsalt thereof.
 16. The composition of claim 15 , wherein said ionomericpolymer is the salt of a sulfonated polyester.
 17. The composition ofclaim 16 , wherein the sulfonated polyester is a linear polyester with ahigh Tg.
 18. The composition of claim 15 , wherein said ionomericpolymer is a acrylic acid polymer or copolymer, or a salt thereof. 19.The composition of claim 15 , wherein said ionomeric polymer is gelatin.20. The composition of claim 19 , wherein said gelatin has a pH of about8 to
 12. 21. The composition of claim 19 , wherein said gelatin has a pHof about 1 to about
 6. 22. The composition according to any one ofclaims 1-3, wherein said polar carrier is a polyol.
 23. The compositionaccording to claim 22 , wherein said polyol is selected from the groupconsisting of ethylene glycol; 1,2-propylene glycol; 1,3-propanediol;2,4-dimethyl-2-ethylhexane-1,3,diol; 2,2-dimethyl-1,3-propanediol;2-ethyl-2-butyl-1,3-propanediol; 2-ethyl-2-isobutyl-1,3-propanediol;1,3-butanediol; 1,4-butanediol; 1,5-pentanediol; 1,6-hexanediol;2,2-4-trimethyl-1,6-hexanediol; thiodiethanol;1,2-cyclohexanedimethanol; 1,3-cyclohexanedimethanol;1,4-cyclohexanedimethanol; 2,2,4,4-tetramethyl-1,3-cyclobutanediol; andp-xylylenediol.
 24. The composition according to claim 22 , wherein saidpolyol is glycerin.
 25. The composition according to any one of claims1-3, further comprising or consisting essentially of a thermoplasticpolymer.
 26. The composition according to any one of claims 1-3, furthercomprising or consisting essentially of a thermoset resin.
 27. Thecomposition according to any one of claims 1-3, wherein the compositionis substantially transparent or translucent.
 28. The composition of anyone of claims 1-3, further comprising an insoluble porous carriersaturated with said composition.
 29. The composition of claim 28 ,wherein said insoluble porous carrier is a thermoplastic web.
 30. Thecomposition of claim 38 , wherein said insoluble porous thermoplasticcarrier web is a non-woven polypropylene (PP).
 31. The composition ofclaim 37 , further comprising a first polyolefin layer and a secondpolyolefin layer disposed on said insoluble porous carrier, wherein saidfirst and second polyolefin layers are bonded or adhered to the porouscarrier by RF heating.
 32. A method of bonding or adhering a firstsubstrate to a second substrate, comprising interposing a compositionbetween the first and second substrates, said composition comprising asusceptor and a polar carrier, wherein said carrier and said susceptorare blended substantially with one another and form a mixture, andwherein said susceptor and/or said carrier are present in amountseffective to allow said composition to be heated by RF energy; andapplying RF energy to said composition to heat said composition, therebycausing the first and second substrates to become adhered or bonded,with the proviso that said susceptor is not a quaternary ammonium salt.33. The method of claim 32 , wherein said RF energy has a frequency inthe range of from about 100 kilohertz to about 5.0 Gigahertz.
 34. Themethod of claim 32 , wherein said RF energy has a frequency in the rangefrom about 10 megahertz to about 30 megahertz.
 35. The method of claim32 , wherein said RF energy has a power of about 0.1 kilowatts to about5 kilowatts.
 36. The method of claim 32 , wherein said polar carriercomprises about 13 to about 30 weight percent of the composition withrespect to said susceptor.
 37. A method of bonding or adhering a firstsubstrate to a second substrate in less than about one second,comprising interposing a composition between the first and secondsubstrates, said composition comprising a susceptor and a polar carrier,wherein said carrier and said susceptor are blended substantially withone another and form a mixture, and wherein said susceptor and/or saidcarrier are present in amounts effective to allow said composition to beheated by RF energy; and applying RF energy to said composition to heatsaid composition, thereby causing the first and second substrates tobecome adhered or bonded in less than about 1 second.
 38. The method ofclaim 37 , wherein said polar carrier comprises about 13 to about 30weight percent of the composition with respect to said susceptor. 39.The method of claim 37 , wherein said composition melts or flows andsaid first and second substrates becomes bonded or adhered in about 100milliseconds to about 1 second.
 40. The method of claim 32 or 37 ,wherein said interposing further comprises coating at least one of thefirst and second substrates with said composition; and placing the firstand second substrates in contact with a uniform pressure applied to thefirst and second substrates.
 41. The method of claim 32 or 37 , whereinsaid interposing comprises interposing said composition between a firstmultilayer stack of the first substrate and a second multilayer stack ofthe second substrate.
 42. The method of claim 32 or 37 , wherein thefirst and second substrates are selected from the group consisting offilm, non-woven, or foamed PP, and film, non-woven, or foamedpolyethelene (PE).
 43. The method of claim 32 or 37 , wherein saidinterposing comprises interposing a composition between the first andsecond substrates, said composition comprising said susceptor, saidpolar carrier, and an adhesive compound, wherein said polar carrier,said adhesive compound, and said susceptor are blended substantiallywith one another and form said mixture.
 44. The method of claim 32 or 37, wherein said susceptor is an ionomeric adhesive.
 45. The method ofclaim 44 , wherein said ionomeric adhesive is a sulfonated polyester orcopolymer thereof, or a salt thereof.
 46. The method of claim 44 ,wherein said ionomeric adhesive is gelatin.
 47. The method of claim 44 ,wherein said ionomeric adhesive is a polyacrylic acid polymer orcopolymer thereof, or a salt thereof.
 48. An adhered or bondedcomposition obtained according to the method of claim 32 or 37 .
 49. Amethod of bonding or adhering a first substrate to a second substrate,comprising: applying a first composition onto the first substrate;applying a second composition onto the second substrate; contacting saidfirst composition with said second composition; applying RF energy tosaid first and second compositions to heat said compositions, therebycausing the first and second substrates to become adhered or bonded;wherein one of said compositions comprises a susceptor and the other ofsaid compositions is a polar carrier, and the susceptor and/or thecarrier are present in amounts effective to allow said first and secondcompositions to be heated by RF energy.
 50. The method of claim 59 ,wherein said susceptor is not a quaternary ammonium salt.
 51. A kit foradhering or bonding a first substrate to a second substrate, comprisingone or more containers, at least one of said containers comprising asusceptor composition, said susceptor composition comprising a susceptorand a polar carrier substantially uniformly dispersed in one another toform a mixture, wherein said susceptor and/or said carrier are presentin amounts effective to allow said composition to be heated by RFenergy.
 52. A kit for adhering or bonding a first substrate to a secondsubstrate, comprising at least two containers, wherein one of saidcontainers comprises a susceptor and another of said containerscomprises a polar carrier, wherein when said susceptor and said carrierare applied to at least one of said first and second substrates and saidsusceptor and carrier are interfaced, a composition is formed that isheatable by RF energy.
 53. The kit of claim 51 or 52 , wherein saidsusceptor is an ionomeric polymer.
 54. The kit of claim 53 , whereinsaid ionomeric polymer is a sulfonated polyester or copolymer thereof,or a salt thereof.
 55. The kit of claim 53 , wherein said ionomericpolymer is an acrylic acid polymer or copolymer thereof, or a saltthereof.
 56. The kit of claim 53 , wherein said ionomeric polymer isgelatin.
 57. A method of making a composition for bonding or adhering,comprising admixing a susceptor and a polar carrier, wherein said polarcarrier and said susceptor are substantially uniformly dispersed in oneanother and form a mixture, and wherein said susceptor and/or saidcarrier is present in amounts effective to allow said composition to beheated by RF energy and wherein said polar carrier comprises about 13 toabout 30 weight percent of the composition with respect to saidsusceptor.
 58. The method of claim 57 , wherein susceptor is anionomeric polymer.
 59. The method of claim 58 , wherein said ionomericpolymer is a sulfonated polyester or copolymer thereof, or a saltthereof.
 60. The method of claim 57 , wherein said ionomeric polymer isan acrylic acid polymer or copolymer thereof, or a salt thereof.
 61. Themethod of claim 57 , wherein said admixing further comprises admixing anadhesive compound, said carrier, and said susceptor, wherein saidcarrier, said adhesive compound, and said susceptor are substantiallyuniformly dispersed in one another and form said mixture.
 62. Acomposition obtained according to the method of claim 57 .
 63. Acomposition comprising an ionomeric polymer and a polar carrier whereinsaid polar carrier comprises about 13 to about 30 weight percent of thecomposition with respect to said polymer.
 64. The composition accordingto claim 63 , wherein said ionomeric polymer is a sulfonated polyesteror a copolymer thereof, or a salt thereof.
 65. The composition accordingto claim 63 , wherein said ionomeric polymer is an acrylic acid polymeror copolymer thereof, or a salt thereof.
 66. The composition accordingto claim 63 , wherein said ionomeric polymer is gelatin.
 67. Thecomposition according to claim 63 , wherein said polar carrier is apolyol.
 68. The composition according to claim 67 , wherein said polyolis selected from the group consisting of ethylene glycol; 1,2-propyleneglycol; 1,3-propanediol; 2,4-dimethyl-2-ethylhexane-1,3,diol;2,2-dimethyl-1,3-propanediol; 2-ethyl-2-butyl-1,3-propanediol;2-ethyl-2-isobutyl-1,3-propanediol; 1,3-butanediol; 1,4-butanediol;1,5-pentanediol; 1,6-hexanediol; 2,2-4-trimethyl-1,6-hexanediol;thiodiethanol; 1,2-cyclohexanedimethanol; 1,3-cyclohexanedimethanol;1,4-cyclohexanedimethanol; 2,2,4,4-tetramethyl-1,3-cyclobutanediol; andp-xylylenediol.
 69. The composition according to claim 67 , wherein saidpolyol is glycerin.
 70. A method of curing a thermoset, comprisingcombining the thermoset with a polar carrier to give a mixture andexposing the mixture to RF energy.
 71. The method of claim 70 , whereinsaid thermoset is an epoxy resin, an acrylic resin, a polyester resin ora urethane resin.
 72. The method of claim 70 , wherein said polarcarrier is a polyol
 73. The composition according to claim 72 , whereinsaid polyol is selected from the group consisting of ethylene glycol;1,2-propylene glycol; 1,3-propanediol; 2,4-dimethyl-2-ethylhexane-1,3,diol; 2,2-dimethyl-1,3-propanediol; 2-ethyl-2-butyl-1,3-propanediol;2-ethyl-2-isobutyl-1,3-propanediol; 1,3-butanediol; 1,4-butanediol;1,5-pentanediol; 1,6-hexanediol; 2,2-4-trimethyl-1,6-hexanediol;thiodiethanol; 1,2-cyclohexanedimethanol; 1,3-cyclohexanedimethanol;1,4-cyclohexanedimethanol; 2,2,4,4-tetramethyl-1,3-cyclobutanediol; andp-xylylenediol.
 74. The composition according to claim 72 , wherein saidpolyol is glycerin.
 75. An apparatus, comprising: a first portion havinga first mating surface; a second portion, having a second matingsurface; a composition disposed between said first mating surface andsaid second mating surface, wherein said composition comprises asusceptor and a polar carrier wherein said susceptor and/or said polarcarrier are present in amounts effective to allow said composition to beheated by RF energy, and wherein said composition adheres said firstmating surface to said second mating surface such that application of aforce to separate said first mating surface and said second matingsurface results in breakage of the apparatus unless said composition isin a melted state.
 76. The apparatus of claim 75 , wherein saidcomposition is disposed on said first mating surface and said secondmating surface such that said composition is not accessible when saidfirst and second mating surfaces are joined.
 77. The apparatus of claim75 , wherein said portion comprises a protrusion from said first matingsurface.
 78. The apparatus of claim 75 , wherein said second portioncomprises a recess formed in said second mating surface.
 79. Theapparatus of claim 77 , further comprising an electronic circuit pathdisposed on said protrusion.
 80. The apparatus of claim 75 , whereinsaid first portion and said second portion may be disassembled uponapplication of RF energy to said composition.
 81. A method for cutting asubstrate, comprising: applying a composition to a portion of thesubstrate, wherein the composition comprises a susceptor and polarcarrier wherein said susceptor and/or said polar carrier are present inamounts effective to allow said composition to be heated by RF energy,and wherein said portion of the substrate defines a first section ofsaid substrate and a second section of said substrate; melting saidportion of the substrate, wherein said melting step includes the step ofheating said composition, wherein the step of heating said compositionincludes the step of applying RF energy to said composition; after saidportion of said substrate has begun to melt, applying a force to saidsubstrate to separate said first section from said second section.
 82. Amethod for dynamically bonding a first adherand to a second adherand,comprising: (1) creating an article of manufacture comprising the firstadherand, the second adherand, and a composition, said composition beingplaced between the first adherand and the second adherand, wherein saidcomposition can be activated in the presence of an RF field; (2) movingthe article of manufacture along a predetermined path; (3) generatingalong a portion of said predetermined path an RF field having sufficientenergy to activate said composition, wherein said composition is exposedto said RF field for no more than about 1 second, and wherein saidcomposition is activated by its less than 1 second exposure to said RFfield.
 83. The method of claim 82 , wherein said article passes throughsaid RF field at a rate of at least about one-thousand feet per minute.84. The method of claim 83 , wherein the article passes through said RFfield at a rate of about 1000 feet per minute.
 85. The method of claim82 , wherein said composition comprises a susceptor and a polar carrier.86. A method for applying a susceptor composition to a substrate,comprising: (1) formulating the susceptor composition as a liquiddispersion; (2) applying said liquid dispersion of said susceptorcomposition to the substrate; (3) drying said susceptor composition,wherein said drying step includes the step of applying RF energy acrossthe composition, thereby generating heat within said liquid dispersion.87. The method of claim 86 , further comprising rolling up the substrateafter the susceptor composition has dried.
 88. A method of bonding oradhering a first substrate to a second substrate, comprising: applying afirst composition onto the first substrate; applying a secondcomposition onto the first composition; contacting the second substratewith the second composition; and applying RF energy to the first andsecond compositions to heat the compositions, thereby causing the firstand second substrates to become adhered or bonded, wherein one of saidcompositions comprises a susceptor and the other of said compositions isa polar carrier, and the susceptor and/or the carrier are present inamounts effective to allow the first and second compositions to beheated by RF energy.
 89. The method according to claim 88 , wherein oneof the compositions comprises at least one susceptor and the other ofthe compositions comprises at least one polar carrier.
 90. A method fordynamically bonding a first substrate to a second substrate, comprising:applying a composition onto the first substrate; after applying saidcomposition onto the first substrate, forming a roll of said firstsubstrate; storing said roll; unrolling said roll; and while unrollingsaid roll: joining an unrolled portion of the first substrate with aportion of the second substrate such that said portion of the secondsubstrate is in contact with a portion of said composition applied ontothe first substrate; and applying RF energy to said portion of saidcomposition, wherein said portion of said composition heats and melts asa result of the RF energy being applied thereto.
 91. A method formanufacturing a radio frequency (RF) active adhesive film, comprising:formulating an RF active adhesive composition into an extrudable resin;providing said extrudable resin to a first extruder; providing athermoplastic to a second extruder; providing a sealing material to athird extruder; layering the output of the first, second, and thirdextruder to form a three layered film, wherein said thermoplastic isdisposed between said sealing material and said RF active adhesivecomposition; and stretching said three layered film.
 92. The method ofclaim 91 , further comprising rolling up said three layered film afterstretching said three layered film.
 93. The method of claim 91 , furthercomprising heating said three layered film prior to stretching saidthree layered film.
 94. A method for manufacturing flexible packaging,comprising: manufacturing a film comprising a first layer comprised of asealing material, a second layer comprised of a thermoplasticcomposition, and a third layer comprised of a radio frequency (RF)active composition, wherein said second layer is disposed between saidfirst layer and said third layer, and wherein said RF active compositioncan be heated by applying a radio signal thereto; applying ink to athermoplastic film; contacting said first film with said thermoplasticfilm to form an assembly, wherein said thermoplastic film is in directcontact with said third layer; applying a radio signal to said assembly;and nipping said assembly.
 95. The method of claim 94 , wherein saidradio signal has a frequency of not more than about 20 MHz.
 96. Themethod of claim 94 , wherein said radio signal has a frequency of notmore than about 15 MHz.
 97. The method of claim 94 , wherein saidthermoplastic film is 70 gauge oriented polypropylene.
 98. The method ofclaim 94 , wherein said radio frequency active composition comprises asusceptor and a polar carrier.
 99. The method of claim 94 , wherein saidradio signal is applied to said assembly for not more than about onesecond.
 100. A seal for sealing a container, comprising: an outer layerof polyethylene; a layer of paper in contact with said outer layer; asecond polyethylene layer in contact with said paper layer; a layercomprising a non-metallic susceptor composition in contact with saidsecond polyethylene layer; a barrier layer in contact with said layercomprising said non-metallic composition; and an inner layer in contactwith said barrier layer, wherein said non-metallic composition heatswhen a radio signal is applied thereto.
 101. The seal of claim 100 ,wherein said non-metallic composition comprises a susceptor and a polarcarrier.
 102. A bookbinding method, comprising: applying a susceptorcomposition to a portion of one side of a substrate, wherein saidsusceptor composition can be heated by applying a radio signal thereto;feeding said substrate into a printing means for printing ink onto saidsubstrate; after said printing means prints ink on said substrate,stacking said substrate with other substrates; applying a radio signalto said stack of substrates, thereby heating said susceptor composition;and nipping the stack.
 103. The method of claim 102 , wherein saidsusceptor composition comprises a susceptor and a polar carrier. 104.The method of claim 103 , wherein said susceptor composition istransparent.
 105. The method of claim 102 , wherein said substratecomprises paper.
 106. A method of assembling a periodical, comprising:coating a plurality of substrates with a composition, wherein thecomposition comprises a susceptor and polar carrier wherein saidsusceptor and/or said polar carrier are present in amounts effective toallow said composition to be heated by RF energy; print ink onto saidplurality of substrates; stacking said plurality of substrates; applyingan electromagnetic field- to said plurality of substrates; and applyingpressure to said plurality of substrates.
 107. An apparatus foractivating a composition using radio frequency (RF) energy, comprising:a direct current (DC) voltage source; an RF amplifier coupled to the DCvoltage source, wherein the DC voltage source provides DC voltage to theRF amplifier; an impedance matching circuit coupled to an output of theRF amplifier; a first probe and a second probe connected to theimpedance matching circuit; and signal generating means, coupled to theRF amplifier, for generating an RF signal, wherein the RF amplifieramplifies the RF signal and the amplified RF signal is provided to theimpedance matching circuit, whereby an RF field is generated at theprobes and the RF field is used to activate the composition.
 108. Theapparatus of claim 107 , wherein the frequency of the RF signal iswithin the about 1 kHz to about 5 GHz frequency band.
 109. The apparatusof claim 107 , wherein the frequency of the RF signal is within theabout 1 MHz to about 80 MHz frequency band.
 110. The apparatus of claim107 , wherein the frequency of the RF signal is within the about 10 MHzto about 15 MHz frequency band.
 111. The apparatus of claim 107 ,wherein the power of the amplified signal is between about 50 watts and2 kilowatts.
 112. The apparatus of claim 107 , wherein the power of theamplified signal is between about 500 watts and 2 kilowatts.
 113. Theapparatus of claim 107 , wherein a DC voltage provided to the RFamplifier by the DC voltage source is between about 50 and 200 dc volts.114. The apparatus of claim 107 , wherein a DC voltage provided to theRF amplifier by the DC voltage source is between about 130 and 200 dcvolts.
 115. The apparatus of claim 107 , wherein the impedance matchingcircuit comprises: a connector for receiving an RF signal; a baluntransformer coupled to the connector; a first and a second variablecapacitor coupled to the balun transformer; and an inductor connectedbetween the first and second variable capacitor.
 116. The apparatus ofclaim 107 , wherein the RF amplifier comprises means for amplifying amilliwatt signal up to a multiple kilowatt continuous wave amplitudesignal with greater than eighty percent power conversion efficiencywhile operating directly from a 100 to 200 VDC power source, with aninstantaneous bandwidth of two-thirds of an octave in the middle HighFrequency RF spectrum between 3 and 30 MHz.
 117. The apparatus of claim107 , further comprising a processor for controlling the frequency ofthe RF signal generated by the signal generating means, and a powersensor coupled to the impedance matching circuit for providing a signalto the processor, wherein the signal is used by the processor incontrolling the frequency of the RF signal generated by the signalgenerating means.
 118. The apparatus of claim 116 , wherein the signalprovided to the processor corresponds to the amount of power reflectedfrom the impedance matching circuit.
 119. The apparatus of claim 116 ,wherein the signal provided to the processor corresponds to the amountof power provided to the impedance matching circuit.
 120. The apparatusof claim 116 , wherein the signal provided to the processor correspondsto the ratio of the amount of power provided to the impedance matchingcircuit and the amount of power reflected from the impedance matchingcircuit.
 121. The apparatus of claim 107 , wherein the first probe is aconductive tube.
 122. The apparatus of claim 121 , wherein the firstprobe has a diameter of about one-eighth of an inch.
 123. The apparatusof claim 107 , wherein one end of the first probe is connected to theimpedance matching circuit and the other end is curled to reduce coronaeffects.
 124. The apparatus of claim 107 , wherein the first probe issinusoidally shaped.
 125. The apparatus of claim 107 , wherein theprobes include a proximal region in which the probes are spaced apart,an activation region in which the probes are proximate to one another,and a distal region in which the probes are spaced apart.
 126. Theapparatus of claim 125 , wherein the probes are substantially parallelto each other in the activation region.
 127. The apparatus of claim 107, further comprising a third probe connected to the impedance matchingcircuit.
 128. The apparatus of claim 107 , wherein the impedancematching circuit comprises an inductor, wherein when the amplified RFsignal is provided to the impedance matching circuit an alternatingcurrent flows through the inductor.
 129. The apparatus of claim 128 ,wherein the first probe, the second probe, and the inductor areconnected in series such that the inductor is connected between thefirst probe and the second probe.
 130. An apparatus for activating acomposition using radio frequency (RF) energy, comprising: a 100 to 200VDC power source; amplifier means for amplifying a milliwatt RF signalup to at least a kilowatt continuous wave amplitude RF signal whileachieving greater than eighty percent power conversion efficiency, theamplifying means achieving an instantaneous bandwidth of two-thirdsoctave in the middle high frequency RF spectrum between 3 MHz and 30MHz, and operating directly from the 100 to VDC power source; signalgenerating means for generating the milliwatt RF signal to be amplifiedby the amplification means; and an impedance matching circuit coupled toan output of the amplification means, wherein the amplification meansamplifies the milliwatt RF signal, and the amplified RF signal isprovided to the impedance matching circuit, whereby an RF field isproduced and the RF field is used to activate the composition.
 131. Theapparatus of claim 130 , further comprising a first probe and a secondprobe connected to the impedance matching circuit.
 132. The apparatus ofclaim 130 , wherein when the amplified RF signal is provided to theimpedance matching circuit an RF field emanates from the probes. 133.The apparatus of claim 132 , wherein the impedance matching circuitcomprises an inductor, wherein the first probe, the second probe, andthe inductor are connected in series, with the inductor being placedbetween the probes.
 134. The apparatus of claim 130 , wherein the firstprobe is a conductive tube.
 135. The apparatus of claim 134 , whereinthe tube is circular and has a diameter of about one-eighth of an inch.136. The apparatus of claim 130 , wherein one end of the probe isconnected to the impedance matching circuit and the other end is curvedto reduce corona effect.
 137. The apparatus of claim 130 , wherein theprobes are sinusoidally shaped.
 138. The apparatus of claim 130 ,further comprising a third probe connected to the impedance matchingcircuit.
 139. A method for inductively liquefying a composition,comprising the steps of: producing an RF signal; amplifying the RFsignal; providing the amplified RF signal to an impedance matchingcircuit comprising a first probe and a second probe, and wherein whenthe amplified RF signal is provided to the impedance matching circuit anRF field is produced at the probes; and placing the composition inproximity to the probes so that the composition is exposed to the RFfield, whereby the composition's exposure to the RF field causes thetemperature of the composition to increase.
 140. The method of claim 139, further comprising the step of controlling the frequency of theamplified RF signal such that the frequency of the amplified RF signalfollows the resonant frequency of the impedance matching circuit whilethe composition is heating.
 141. The method of claim 139 , wherein thefrequency of the RF signal is between about 1 kHz and about 5 GHz. 142.The method of claim 139 , wherein the frequency of the RF signal isbetween about 1 MHz and about 80 MHz.
 143. The method of claim 139 ,wherein the frequency of the RF signal is between about 10 MHz and 15MHz.
 144. The method of claim 139 , wherein the composition is exposedto the RF field for not more than about 1 second.
 145. The method ofclaim 139 , wherein the composition is exposed to the RF field for notmore than about 0.1 seconds.
 146. The method of claim 139 , wherein thecomposition is exposed to the RF field for not more than about 0.075seconds.
 147. The method of claim 139 , wherein the power of the RFsignal provided to the impedance matching circuit is about 50 watts to 2kilowatts.
 148. The method of claim 139 , wherein the compositioncomprises an ionomeric polymer and a polar carrier.
 149. A method forheating a composition comprising an ionomeric polymer and a polarcarrier, the method comprising the steps of: generating an RF signal;using the RF signal to generate an RF field; and exposing thecomposition to the RF field.
 150. The method of claim 149 , wherein thecomposition is exposed to the RF field for not more than about 1 second.151. The method of claim 149 , wherein the composition is exposed to theRF field for not more than about 0.5 seconds.
 152. The method of claim149 , wherein the composition is exposed to the RF field for not morethan about 0.1 seconds.
 153. The method of claim 149 , wherein thecomposition is exposed to the RF field for not more than about 0.075seconds.
 154. The method of claim 149 , wherein the frequency of the RFsignal is between 1 kHz and 5 GHz.
 155. The method of claim 149 ,wherein the frequency of the RF signal is between 1 MHz and 80 MHz. 156.The method of claim 149 , wherein the frequency of the RF signal isbetween 10 MHz and 15 MHz.
 157. An interdigitated probe system,comprising: a first element comprising a first conductor and one or moresecond conductors connected to the first conductor; and a second elementcomprising a first conductor and one or more second conductors connectedto the first conductor, wherein the first element and the second elementare orientated such that the one or more second conductors of the firstelement are coplanar with the one or more second conductors of thesecond element and each one of the one or more second conductors of thefirst element are adjacent to at least one of the one or more secondconductors of the second element.
 158. An apparatus for activating asample, comprising: an alternating voltage supply; a first outputterminal and a second output terminal coupled to said alternatingvoltage supply, wherein an alternating voltage is produced between saidfirst and second output terminals; and a first probe coupled to firstoutput terminal and a second probe coupled to said second outputterminal.
 159. The apparatus of claim 107 , wherein said probes includea proximal region in which said probes are spaced apart, an activationregion in which said probes are proximate to one another, and a distalregion in which said probes are spaced apart.
 160. The apparatus ofclaim 107 , wherein said probes are conductive tubes.